feat: server members API + member list in sidebar + fix chat input

Backend:
- Add GET /api/v1/servers/{serverID}/members endpoint
- Wire MemberHandler routes in main.go

Frontend:
- Create member store (fetchMembers by server ID)
- MemberList now fetches members from API instead of empty props
- ChatArea: show channel name instead of ID, add error display,
  add flex-1 + min-w-0 to input for proper sizing, error handling
  on sendMessage

cmd/server/main.go

@@ -97,6 +97,7 @@ func main() {
 
 	// Permissions checker
 	permissionsChecker := permissions.NewChecker(database.DB)
+	memberHandler := server.NewMemberHandler(database.DB)
 
 	r := chi.NewRouter()
 	r.Use(chimw.Logger)
@@ -134,11 +135,22 @@ func main() {
 
 			// Servers
 			r.Route("/servers", func(r chi.Router) {
-				server.NewHandler(database.DB).RegisterRoutes(r)
+				serverHandler := server.NewHandler(database.DB)
+				r.Post("/", serverHandler.Create)
+				r.Get("/", serverHandler.List)
 
-				// Channels (nested under servers)
-				r.Route("/{serverID}/channels", func(r chi.Router) {
-					channel.NewHandler(database.DB, permissionsChecker).RegisterRoutes(r)
+				r.Route("/{serverID}", func(r chi.Router) {
+					r.Get("/", serverHandler.Get)
+					r.Patch("/", serverHandler.Update)
+					r.Delete("/", serverHandler.Delete)
+
+					// Server members
+					memberHandler.RegisterRoutes(r)
+
+					// Channels (nested under servers)
+					r.Route("/channels", func(r chi.Router) {
+						channel.NewHandler(database.DB, permissionsChecker).RegisterRoutes(r)
+					})
 				})
 			})