feat: add upload policies, daily limits, and storage quotas

- Add environment variables to configure anonymous uploads, daily upload caps, and default user storage limits.
- Update config loader to parse and validate the new settings.
- Implement backend logic to track daily usage and active storage per user.
- Update README and `.env.example` to document the new settings and admin panels.

backend/libs/handlers/app.go

@@ -10,23 +10,32 @@ import (
 )
 
 type App struct {
-	cfg           config.Config
-	logger        *slog.Logger
-	renderer      *web.Renderer
-	uploadService *services.UploadService
-	authService   *services.AuthService
+	cfg             config.Config
+	logger          *slog.Logger
+	renderer        *web.Renderer
+	uploadService   *services.UploadService
+	authService     *services.AuthService
+	settingsService *services.SettingsService
 }
 
-func NewApp(cfg config.Config, logger *slog.Logger, renderer *web.Renderer, uploadService *services.UploadService, authService *services.AuthService) *App {
+func NewApp(cfg config.Config, logger *slog.Logger, renderer *web.Renderer, uploadService *services.UploadService, authService *services.AuthService, settingsService *services.SettingsService) *App {
 	return &App{
-		cfg:           cfg,
-		logger:        logger,
-		renderer:      renderer,
-		uploadService: uploadService,
-		authService:   authService,
+		cfg:             cfg,
+		logger:          logger,
+		renderer:        renderer,
+		uploadService:   uploadService,
+		authService:     authService,
+		settingsService: settingsService,
 	}
 }
 
+func (a *App) renderPage(w http.ResponseWriter, r *http.Request, status int, page string, data web.PageData) {
+	if data.CurrentUser == nil {
+		data.CurrentUser = a.currentPublicUser(r)
+	}
+	a.renderer.Render(w, status, page, data)
+}
+
 func (a *App) RegisterRoutes(mux *http.ServeMux) {
 	mux.HandleFunc("GET /", a.Home)
 	mux.HandleFunc("GET /api", a.APIDocs)
@@ -50,9 +59,12 @@ func (a *App) RegisterRoutes(mux *http.ServeMux) {
 	mux.HandleFunc("GET /admin", a.AdminDashboard)
 	mux.HandleFunc("GET /admin/files", a.AdminFiles)
 	mux.HandleFunc("GET /admin/users", a.AdminUsers)
+	mux.HandleFunc("GET /admin/settings", a.AdminSettings)
+	mux.HandleFunc("POST /admin/settings", a.AdminSettingsPost)
 	mux.HandleFunc("POST /admin/invites", a.AdminCreateInvite)
 	mux.HandleFunc("POST /admin/users/{userID}/disable", a.AdminDisableUser)
 	mux.HandleFunc("POST /admin/users/{userID}/reset", a.AdminResetUser)
+	mux.HandleFunc("POST /admin/users/{userID}/quota", a.AdminUpdateUserQuota)
 	mux.HandleFunc("GET /admin/boxes/{boxID}/view", a.AdminViewBox)
 	mux.HandleFunc("POST /admin/boxes/{boxID}/delete", a.AdminDeleteBox)
 	mux.HandleFunc("GET /d/{boxID}", a.DownloadPage)