PAP-10430: split Issue-to-Task copy migration (#7651)

## Thinking Path

> - Paperclip is the open source app people use to manage AI agents for
work.
> - The board UI is the operator surface where users create, assign,
monitor, and review work items.
> - The product language is moving toward "tasks" for user-facing work
items while the internal API and database still use "issues".
> - PR #7543 bundled this copy migration with broader
information-architecture work, which made the branch too large for
Greptile review.
> - This pull request peels the Issue-to-Task copy migration into a
smaller, independently reviewable change.
> - The benefit is clearer user-facing terminology, less agent confusion
via the Paperclip skill note, and a smaller PR that Greptile can review.

## Linked Issues or Issue Description

Refs #7645
Refs #7543
Refs PAP-10430

This PR was split out of #7543 so the Issue-to-Task copy migration can
be reviewed separately and the remaining IA PR can fall under Greptile's
file limit.

## What Changed

- Preserves Scott Tong's original `PAP-57` copy-only commit, with author
and co-author credit intact, to rename user-facing "Issues" copy to
"Tasks" across the UI while keeping routes/API/internal symbols as
`issue`.
- Updates onboarding and release-smoke browser selectors from `Create &
Open Issue` to `Create & Open Task`.
- Adds a terminology note to `skills/paperclip/SKILL.md` clarifying that
task and issue refer to the same Paperclip work item.
- Resolves the only cherry-pick conflict by keeping current search
artifacts support and changing visible search copy to "tasks".

## Verification

- `pnpm --filter @paperclipai/ui build` passed.
- `NODE_ENV=test pnpm exec vitest run
ui/src/components/IssuesList.test.tsx ui/src/components/Sidebar.test.tsx
ui/src/components/NewIssueDialog.test.tsx
ui/src/pages/IssueDetail.test.tsx` passed: 4 files, 66 tests.
- `git diff --check origin/master...HEAD` passed.
- Diff is 80 files, below Greptile's 100-file limit.
- Before/after UI copy examples: "Issues" -> "Tasks", "New Issue" ->
"New Task", "Create & Open Issue" -> "Create & Open Task".

## Risks

- Medium copy-risk: this intentionally changes user-facing terminology
broadly while keeping internal issue identifiers and routes unchanged.
- Some docs and APIs still say `issue`; the skill note clarifies this so
agents do not treat task and issue as separate entities.
- Browser-level visual validation is expected from CI because this local
container is missing usable browser dependencies.

> For core feature work, check [`ROADMAP.md`](ROADMAP.md) first and
discuss it in `#dev` before opening the PR. Feature PRs that overlap
with planned core work may need to be redirected — check the roadmap
first. See `CONTRIBUTING.md`.

## Model Used

Scott Tong authored the original `PAP-57` copy migration, assisted by
Claude Opus 4.8 and Paperclip agents per the preserved commit metadata.
Codex / GPT-5-class coding agent with shell, GitHub CLI, and repository
access performed the PR split, conflict resolution, skill note, and
verification.

## Checklist

- [x] I have included a thinking path that traces from project context
to this change
- [x] I have specified the model used (with version and capability
details)
- [x] I have checked ROADMAP.md and confirmed this PR does not duplicate
planned core work
- [x] I have searched GitHub for duplicate or related PRs and linked
them above
- [x] I have either (a) linked existing issues with `Fixes: #` / `Closes
#` / `Refs #` OR (b) described the issue in-PR following the relevant
issue template
- [x] I have run tests locally and they pass
- [x] I have added or updated tests where applicable
- [x] If this change affects the UI, I have included before/after
screenshots
- [x] I have updated relevant documentation to reflect my changes
- [x] I have considered and documented any risks above
- [x] All Paperclip CI gates are green
- [x] Greptile is 5/5 with no open P2s, recommendations, or follow-ups
- [x] I will address all Greptile and reviewer comments before
requesting merge

---------

Co-authored-by: scotttong <scott.tong@gmail.com>
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
Co-authored-by: Paperclip <noreply@paperclip.ing>

ui/src/pages/DesignGuide.tsx

@@ -470,7 +470,7 @@ export function DesignGuide() {
 
         <SubSection title="With icons">
           <div className="flex items-center gap-2 flex-wrap">
-            <Button><Plus /> New Issue</Button>
+            <Button><Plus /> New Task</Button>
             <Button variant="outline"><Upload /> Upload</Button>
             <Button variant="destructive"><Trash2 /> Delete</Button>
             <Button size="sm"><Plus /> Add</Button>
@@ -727,11 +727,11 @@ export function DesignGuide() {
               checked={menuChecked}
               onCheckedChange={(value) => setMenuChecked(value === true)}
             >
-              Watch issue
+              Watch task
             </DropdownMenuCheckboxItem>
             <DropdownMenuItem variant="destructive">
               <Trash2 className="h-4 w-4" />
-              Delete issue
+              Delete task
             </DropdownMenuItem>
           </DropdownMenuContent>
         </DropdownMenu>
@@ -784,7 +784,7 @@ export function DesignGuide() {
           </SheetTrigger>
           <SheetContent side="right">
             <SheetHeader>
-              <SheetTitle>Issue Properties</SheetTitle>
+              <SheetTitle>Task Properties</SheetTitle>
               <SheetDescription>Edit metadata without leaving the current page.</SheetDescription>
             </SheetHeader>
             <div className="space-y-4 px-4">
@@ -836,7 +836,7 @@ export function DesignGuide() {
                 </CommandItem>
                 <CommandItem>
                   <CircleDot className="h-4 w-4" />
-                  Issues
+                  Tasks
                 </CommandItem>
               </CommandGroup>
               <CommandSeparator />
@@ -847,7 +847,7 @@ export function DesignGuide() {
                 </CommandItem>
                 <CommandItem>
                   <Plus className="h-4 w-4" />
-                  Create new issue
+                  Create new task
                 </CommandItem>
               </CommandGroup>
             </CommandList>
@@ -870,7 +870,7 @@ export function DesignGuide() {
             </BreadcrumbItem>
             <BreadcrumbSeparator />
             <BreadcrumbItem>
-              <BreadcrumbPage>Issue List</BreadcrumbPage>
+              <BreadcrumbPage>Task List</BreadcrumbPage>
             </BreadcrumbItem>
           </BreadcrumbList>
         </Breadcrumb>
@@ -899,7 +899,7 @@ export function DesignGuide() {
         <SubSection title="Metric Cards">
           <div className="grid md:grid-cols-2 xl:grid-cols-4 gap-4">
             <MetricCard icon={Bot} value={12} label="Active Agents" description="+3 this week" />
-            <MetricCard icon={CircleDot} value={48} label="Open Issues" />
+            <MetricCard icon={CircleDot} value={48} label="Open Tasks" />
             <MetricCard icon={DollarSign} value="$1,234" label="Monthly Cost" description="Under budget" />
             <MetricCard icon={Zap} value="99.9%" label="Uptime" />
           </div>
@@ -1298,7 +1298,7 @@ export function DesignGuide() {
             </div>
             <div className="flex items-center gap-2 px-3 py-1.5 rounded-md text-sm font-medium text-muted-foreground hover:bg-accent/50 hover:text-accent-foreground cursor-pointer">
               <CircleDot className="h-4 w-4" />
-              Issues
+              Tasks
               <span className="ml-auto text-xs bg-primary text-primary-foreground rounded-full px-1.5 py-0.5">
                 12
               </span>
@@ -1331,7 +1331,7 @@ export function DesignGuide() {
       {/* ============================================================ */}
       {/*  GROUPED LIST (Issues pattern)                                */}
       {/* ============================================================ */}
-      <Section title="Grouped List (Issues pattern)">
+      <Section title="Grouped List (Tasks pattern)">
         <div>
           <div className="flex items-center gap-2 px-4 py-2 bg-muted/50 rounded-t-md">
             <StatusIcon status="in_progress" />
@@ -1588,7 +1588,7 @@ export function DesignGuide() {
         <div className="border border-border rounded-md divide-y divide-border text-sm">
           {[
             ["Cmd+K / Ctrl+K", "Open Command Palette"],
-            ["C", "New Issue (outside inputs)"],
+            ["C", "New Task (outside inputs)"],
             ["[", "Toggle Sidebar"],
             ["]", "Toggle Properties Panel"],
 
@@ -1604,7 +1604,7 @@ export function DesignGuide() {
         </div>
       </Section>
 
-      <Section title="Issue Output Surface">
+      <Section title="Task Output Surface">
         <SubSection title="Multiple outputs (primary video + 'Also produced')">
           <IssueOutputSection workProducts={DESIGN_GUIDE_OUTPUTS} />
         </SubSection>
@@ -1613,7 +1613,7 @@ export function DesignGuide() {
         </SubSection>
         <SubSection title="Empty state">
           <p className="text-xs text-muted-foreground">
-            When an issue has produced no artifact work products, the Output section renders nothing
+            When a task has produced no artifact work products, the Output section renders nothing
             at all (no placeholder card).
           </p>
         </SubSection>