fix: scope environments "Test provider" button to clicked row (#8380)

## Thinking Path

> - Paperclip is the open source app people use to manage AI agents for
work
> - Agents run inside environments, and the Environments settings page
lets users configure each environment and verify it with a "Test
provider" / "Test connection" button per row
> - When a user clicked one environment's test button, every environment
row's button switched to the disabled "Testing..." state at the same
time, then all flipped back together
> - That happened because all rows read the same shared
`environmentProbeMutation.isPending` flag, so a single in-flight probe
disabled and relabeled every button
> - This is confusing: it looks like every environment is being tested,
and it blocks interacting with other rows while one probe runs
> - This pull request tracks the specific environment id being probed in
dedicated state and scopes the disabled/label logic to that id
> - The benefit is that only the button the user actually clicked shows
"Testing..." and is disabled, while the other rows stay interactive

## Linked Issues or Issue Description

No public GitHub issue exists, so the bug is described inline below
following the bug report template.

### What happened?

On the Environments settings page, clicking "Test provider" on one
environment caused the test button on *every* environment row to change
to "Testing..." and become disabled at the same time, then all reverted
together when the probe finished.

### Expected behavior

Only the button for the environment the user clicked should show
"Testing..." and be disabled while its probe runs. Every other row's
button should stay enabled and unchanged.

### Steps to reproduce

1. Open instance settings → Environments with two or more configured
environments.
2. Click "Test provider" / "Test connection" on a single row.
3. Observe that all rows' buttons enter the "Testing..." disabled state
simultaneously instead of just the clicked one.

### Paperclip version or commit

`master` at commit a10f17800 (branch
`fix/environments-test-provider-button-scope`).

### Deployment mode

Local dev (`pnpm dev`). UI-only; reproduces independent of backend.

## What Changed

- Added a dedicated `testingEnvironmentId` state in
`ui/src/pages/CompanyEnvironments.tsx` to track which environment is
currently being probed.
- Set it in the probe mutation's `onMutate` and clear it in `onSettled`,
and reset it when the selected company changes.
- Scoped the test button's `disabled` state and `"Testing..."` label to
`testingEnvironmentId === environment.id` instead of the shared
`environmentProbeMutation.isPending` flag.
- Added `ui/src/pages/CompanyEnvironments.test.tsx` verifying that
clicking one environment's test button puts only that row into the
"Testing..." disabled state while other rows stay enabled.

## Verification

- `pnpm typecheck` (UI) passes clean.
- `vitest run src/pages/CompanyEnvironments.test.tsx` passes (new test
fails against the old shared-`isPending` behavior, confirming it guards
the fix).
- Manual: on the Environments page with multiple environments, click one
row's test button and confirm only that button shows "Testing..." / is
disabled while the others remain enabled, then it reverts on completion.

## Risks

- Low risk. Single-file UI change scoped to per-row button state; no
API, schema, or behavior changes to the probe itself. The probe mutation
still runs identically — only which buttons reflect the pending state
changed.

## Model Used

- Claude Opus 4.8 (Anthropic), `claude-opus-4-8`, with extended
reasoning and tool use, via Claude Code.

## 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 not referenced internal/instance-local Paperclip issues or
links (only public GitHub `#NNN` / `github.com/paperclipai/paperclip`
URLs)
- [x] My branch name describes the change and contains no internal
Paperclip ticket id or instance-derived details
- [x] I have run tests locally and they pass
- [x] I have added or updated tests where applicable
- [ ] If this change affects the UI, I have included before/after
screenshots
- [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

ui/src/pages/CompanyEnvironments.tsx

@@ -166,6 +166,7 @@ export function CompanyEnvironments() {
   const [editingEnvironmentId, setEditingEnvironmentId] = useState<string | null>(null);
   const [environmentForm, setEnvironmentForm] = useState<EnvironmentFormState>(createEmptyEnvironmentForm);
   const [probeResults, setProbeResults] = useState<Record<string, EnvironmentProbeResult | null>>({});
+  const [testingEnvironmentId, setTestingEnvironmentId] = useState<string | null>(null);
 
   useEffect(() => {
     setBreadcrumbs([
@@ -232,6 +233,12 @@ export function CompanyEnvironments() {
 
   const environmentProbeMutation = useMutation({
     mutationFn: async (environmentId: string) => await environmentsApi.probe(environmentId),
+    onMutate: (environmentId) => {
+      setTestingEnvironmentId(environmentId);
+    },
+    onSettled: (_probe, _error, environmentId) => {
+      setTestingEnvironmentId((current) => (current === environmentId ? null : current));
+    },
     onSuccess: (probe, environmentId) => {
       setProbeResults((current) => ({
         ...current,
@@ -287,6 +294,7 @@ export function CompanyEnvironments() {
     setEditingEnvironmentId(null);
     setEnvironmentForm(createEmptyEnvironmentForm());
     setProbeResults({});
+    setTestingEnvironmentId(null);
   }, [selectedCompanyId]);
 
   function handleEditEnvironment(environment: Environment) {
@@ -530,9 +538,9 @@ export function CompanyEnvironments() {
                           size="sm"
                           variant="outline"
                           onClick={() => environmentProbeMutation.mutate(environment.id)}
-                          disabled={environmentProbeMutation.isPending}
+                          disabled={testingEnvironmentId === environment.id}
                         >
-                          {environmentProbeMutation.isPending
+                          {testingEnvironmentId === environment.id
                             ? "Testing..."
                             : environment.driver === "ssh"
                               ? "Test connection"