fix: golangci-lint v2 config and lint-clean production code

- Fix .golangci.yml for v2 format (linters-settings -> linters.settings)
- All production code now passes golangci-lint with zero issues
- Line length 88, funlen 80/50, cyclop 15, dupl 100
- Extract shared helpers in db (scanChannels, scanInt64s, scanMessages)
- Split runMigrations into applyMigration/execMigration
- Fix fanOut return signature (remove unused int64)
- Add fanOutSilent helper to avoid dogsled
- Rewrite CLI code for lint compliance (nlreturn, wsl_v5, noctx, etc)
- Rename CLI api package to chatapi to avoid revive var-naming
- Fix all noinlineerr, mnd, perfsprint, funcorder issues
- Fix db tests: extract helpers, add t.Parallel, proper error checks
- Broker tests already clean
- Handler integration tests still have lint issues (next commit)

internal/server/routes.go

@@ -16,7 +16,7 @@ import (
 
 const routeTimeout = 60 * time.Second
 
-// SetupRoutes configures the HTTP routes and middleware chain.
+// SetupRoutes configures the HTTP routes and middleware.
 func (s *Server) SetupRoutes() {
 	s.router = chi.NewRouter()
 
@@ -39,13 +39,19 @@ func (s *Server) SetupRoutes() {
 	}
 
 	// Health check
-	s.router.Get("/.well-known/healthcheck.json", s.h.HandleHealthCheck())
+	s.router.Get(
+		"/.well-known/healthcheck.json",
+		s.h.HandleHealthCheck(),
+	)
 
 	// Protected metrics endpoint
 	if viper.GetString("METRICS_USERNAME") != "" {
 		s.router.Group(func(r chi.Router) {
 			r.Use(s.mw.MetricsAuth())
-			r.Get("/metrics", http.HandlerFunc(promhttp.Handler().ServeHTTP))
+			r.Get("/metrics",
+				http.HandlerFunc(
+					promhttp.Handler().ServeHTTP,
+				))
 		})
 	}
 
@@ -53,55 +59,66 @@ func (s *Server) SetupRoutes() {
 	s.router.Route("/api/v1", func(r chi.Router) {
 		r.Get("/server", s.h.HandleServerInfo())
 		r.Post("/session", s.h.HandleCreateSession())
-
-		// Unified state and message endpoints
 		r.Get("/state", s.h.HandleState())
 		r.Get("/messages", s.h.HandleGetMessages())
 		r.Post("/messages", s.h.HandleSendCommand())
 		r.Get("/history", s.h.HandleGetHistory())
-
-		// Channels
 		r.Get("/channels", s.h.HandleListAllChannels())
-		r.Get("/channels/{channel}/members", s.h.HandleChannelMembers())
+		r.Get(
+			"/channels/{channel}/members",
+			s.h.HandleChannelMembers(),
+		)
 	})
 
 	// Serve embedded SPA
+	s.setupSPA()
+}
+
+func (s *Server) setupSPA() {
 	distFS, err := fs.Sub(web.Dist, "dist")
 	if err != nil {
-		s.log.Error("failed to get web dist filesystem", "error", err)
-	} else {
-		fileServer := http.FileServer(http.FS(distFS))
-
-		s.router.Get("/*", func(w http.ResponseWriter, r *http.Request) {
-			s.serveSPA(distFS, fileServer, w, r)
-		})
-	}
-}
-
-func (s *Server) serveSPA(
-	distFS fs.FS,
-	fileServer http.Handler,
-	w http.ResponseWriter,
-	r *http.Request,
-) {
-	readFS, ok := distFS.(fs.ReadFileFS)
-	if !ok {
-		http.Error(w, "filesystem error", http.StatusInternalServerError)
+		s.log.Error(
+			"failed to get web dist filesystem",
+			"error", err,
+		)
 
 		return
 	}
 
-	// Try to serve the file; fall back to index.html for SPA routing.
-	f, err := readFS.ReadFile(r.URL.Path[1:])
-	if err != nil || len(f) == 0 {
-		indexHTML, _ := readFS.ReadFile("index.html")
+	fileServer := http.FileServer(http.FS(distFS))
 
-		w.Header().Set("Content-Type", "text/html; charset=utf-8")
-		w.WriteHeader(http.StatusOK)
-		_, _ = w.Write(indexHTML)
+	s.router.Get("/*", func(
+		w http.ResponseWriter,
+		r *http.Request,
+	) {
+		readFS, ok := distFS.(fs.ReadFileFS)
+		if !ok {
+			fileServer.ServeHTTP(w, r)
 
-		return
-	}
+			return
+		}
 
-	fileServer.ServeHTTP(w, r)
+		f, readErr := readFS.ReadFile(r.URL.Path[1:])
+		if readErr != nil || len(f) == 0 {
+			indexHTML, indexErr := readFS.ReadFile(
+				"index.html",
+			)
+			if indexErr != nil {
+				http.NotFound(w, r)
+
+				return
+			}
+
+			w.Header().Set(
+				"Content-Type",
+				"text/html; charset=utf-8",
+			)
+			w.WriteHeader(http.StatusOK)
+			_, _ = w.Write(indexHTML)
+
+			return
+		}
+
+		fileServer.ServeHTTP(w, r)
+	})
 }