feat: add emoji reaction support for files

- Implement `ReactionService` to manage file reactions in the database.
- Add `POST /d/{boxID}/f/{fileID}/react` endpoint to handle user reactions.
- Add `GET /emoji/{pack}/{file}` endpoint to serve custom emoji assets.
- Support loading custom emoji packs dynamically from the data directory.
- Update README with instructions on configuring emoji reaction packs.

backend/libs/handlers/app.go

@@ -16,12 +16,13 @@ type App struct {
 	uploadService   *services.UploadService
 	authService     *services.AuthService
 	settingsService *services.SettingsService
+	reactionService *services.ReactionService
 	banService      *services.BanService
 	rateLimiter     *rateLimiter
 	uploadGroups    *uploadGrouper
 }
 
-func NewApp(cfg config.Config, logger *slog.Logger, renderer *web.Renderer, uploadService *services.UploadService, authService *services.AuthService, settingsService *services.SettingsService, banService *services.BanService) *App {
+func NewApp(cfg config.Config, logger *slog.Logger, renderer *web.Renderer, uploadService *services.UploadService, authService *services.AuthService, settingsService *services.SettingsService, reactionService *services.ReactionService, banService *services.BanService) *App {
 	return &App{
 		cfg:             cfg,
 		logger:          logger,
@@ -29,6 +30,7 @@ func NewApp(cfg config.Config, logger *slog.Logger, renderer *web.Renderer, uplo
 		uploadService:   uploadService,
 		authService:     authService,
 		settingsService: settingsService,
+		reactionService: reactionService,
 		banService:      banService,
 		rateLimiter:     newRateLimiter(),
 		uploadGroups:    newUploadGrouper(),
@@ -121,6 +123,7 @@ func (a *App) RegisterRoutes(mux *http.ServeMux) {
 	mux.HandleFunc("GET /d/{boxID}/manage/{token}/delete", a.ManageDeleteBox)
 	mux.HandleFunc("POST /d/{boxID}/unlock", a.UnlockBox)
 	mux.HandleFunc("GET /d/{boxID}/zip", a.DownloadZip)
+	mux.HandleFunc("POST /d/{boxID}/f/{fileID}/react", a.ReactToFile)
 	mux.HandleFunc("GET /d/{boxID}/f/{fileID}", a.DownloadFile)
 	mux.HandleFunc("GET /d/{boxID}/f/{fileID}/download", a.DownloadFileContent)
 	mux.HandleFunc("GET /d/{boxID}/thumb/{fileID}", a.Thumbnail)
@@ -132,5 +135,6 @@ func (a *App) RegisterRoutes(mux *http.ServeMux) {
 	mux.HandleFunc("GET /api/v1/schemas/upload-request.json", a.UploadRequestSchema)
 	mux.HandleFunc("GET /api/v1/schemas/upload-response.json", a.UploadResponseSchema)
 	mux.HandleFunc("POST /api/v1/upload", a.Upload)
+	mux.HandleFunc("GET /emoji/{pack}/{file}", a.EmojiAsset)
 	mux.Handle("GET /static/", a.Static())
 }