Add configuration files and update project documentation

- Introduced .editorconfig for consistent coding styles across the project.
- Added .golangci.yml for Go linting configuration.
- Updated AGENTS.md to clarify project structure and components.
- Enhanced CONTRIBUTING.md with Makefile usage for common tasks.
- Updated Dockerfiles to use Go 1.24 and improved build instructions.
- Refined README.md and deployment documentation for clarity.
- Added testing documentation in testing.md for backend and frontend tests.
- Introduced Makefile for streamlined development commands and tasks.

internal/app/router.go

@@ -9,29 +9,27 @@ import (
 // APIHandler is the interface for API routing (implemented by handlers.Handlers).
 type APIHandler interface {
 	APIRouter(rw http.ResponseWriter, req *http.Request)
+	ClientRouter(rw http.ResponseWriter, req *http.Request)
+	RedirectLogout(rw http.ResponseWriter, req *http.Request)
+	WatchGridUpdates(rw http.ResponseWriter, req *http.Request)
+	GridTile(rw http.ResponseWriter, req *http.Request)
 }
 
 // Router returns the HTTP router for the app.
-// publicDir is used for /js/ static file serving (e.g. "public").
-// apiHandler handles /map/api/* requests; if nil, uses built-in apiRouter.
-func (a *App) Router(publicDir string, apiHandler APIHandler) http.Handler {
+func (a *App) Router(publicDir string, h APIHandler) http.Handler {
 	r := chi.NewRouter()
 
 	r.Handle("/js/*", http.FileServer(http.Dir(publicDir)))
-	r.HandleFunc("/client/*", a.client)
-	r.HandleFunc("/logout", a.redirectLogout)
+	r.HandleFunc("/client/*", h.ClientRouter)
+	r.HandleFunc("/logout", h.RedirectLogout)
 
 	r.Route("/map", func(r chi.Router) {
-		if apiHandler != nil {
-			r.HandleFunc("/api/*", apiHandler.APIRouter)
-		} else {
-			r.HandleFunc("/api/*", a.apiRouter)
-		}
-		r.HandleFunc("/updates", a.watchGridUpdates)
-		r.Handle("/grids/*", http.StripPrefix("/map/grids", http.HandlerFunc(a.gridTile)))
+		r.HandleFunc("/api/*", h.APIRouter)
+		r.HandleFunc("/updates", h.WatchGridUpdates)
+		r.Handle("/grids/*", http.StripPrefix("/map/grids", http.HandlerFunc(h.GridTile)))
 	})
 
-	r.HandleFunc("/*", a.serveSPARoot)
+	r.HandleFunc("/*", a.ServeSPARoot)
 
 	return r
 }