refactor: simplify PWA handlers and fix review findings

Address code review findings from reuse, quality, and efficiency agents:

- Cache manifest JSON and service worker JS at init (was rebuilt per
  request with allocations and JSON encoding on every hit)
- Add ImagePathsByUser store method for targeted image cleanup (was
  loading 100k full fave objects just to read image_path)
- Add missing aria-label on privacy toggle in fave_list.html (inline
  copy had drifted from the partial — accessibility bug)
- Fix comment/function name mismatch in pwa.go
- Remove redundant user nil-check in handleShare (requireLogin guards)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

internal/handler/admin.go

@@ -218,12 +218,10 @@ func (h *Handler) handleAdminDeleteUser(w http.ResponseWriter, r *http.Request)
 	}
 
 	// Delete user's images from disk before database deletion.
-	faves, _, _ := h.deps.Faves.ListByUser(id, 100000, 0)
-	for _, f := range faves {
-		if f.ImagePath != "" {
-			if delErr := image.Delete(h.deps.Config.UploadDir, f.ImagePath); delErr != nil {
-				slog.Error("image delete error", "fave_id", f.ID, "error", delErr)
-			}
+	imagePaths, _ := h.deps.Faves.ImagePathsByUser(id)
+	for _, p := range imagePaths {
+		if delErr := image.Delete(h.deps.Config.UploadDir, p); delErr != nil {
+			slog.Error("image delete error", "error", delErr)
 		}
 	}
 	if user.AvatarPath != "" {

internal/handler/handler.go

@@ -32,14 +32,20 @@ type Deps struct {
 type Handler struct {
 	deps        Deps
 	rateLimiter *middleware.RateLimiter
+
+	// Cached PWA responses (computed once at init, never change).
+	manifestJSON []byte
+	swJS         []byte
 }
 
 // New creates a new Handler with the given dependencies.
 func New(deps Deps) *Handler {
-	return &Handler{
+	h := &Handler{
 		deps:        deps,
 		rateLimiter: middleware.NewRateLimiter(deps.Config.RateLimit),
 	}
+	h.initPWACache()
+	return h
 }
 
 // RateLimiterCleanupLoop periodically evicts stale rate limiter entries.

internal/handler/pwa.go

@@ -14,8 +14,9 @@ import (
 	"kode.naiv.no/olemd/favoritter/web"
 )
 
-// handleManifest serves the Web App Manifest with dynamic BasePath injection.
-func (h *Handler) handleManifest(w http.ResponseWriter, r *http.Request) {
+// initPWACache pre-computes the manifest JSON and service worker JS
+// so they can be served without per-request allocations.
+func (h *Handler) initPWACache() {
 	bp := h.deps.Config.BasePath
 
 	manifest := map[string]any{
@@ -42,44 +43,33 @@ func (h *Handler) handleManifest(w http.ResponseWriter, r *http.Request) {
 			},
 		},
 	}
+	h.manifestJSON, _ = json.Marshal(manifest)
 
-	w.Header().Set("Content-Type", "application/manifest+json")
-	json.NewEncoder(w).Encode(manifest)
+	staticFS, err := fs.Sub(web.StaticFS, "static")
+	if err == nil {
+		if data, err := fs.ReadFile(staticFS, "sw.js"); err == nil {
+			h.swJS = []byte(strings.ReplaceAll(string(data), "{{BASE_PATH}}", bp))
+		}
+	}
 }
 
-// handleServiceWorker serves the service worker JS from root scope.
-// BasePath is injected via placeholder replacement so the SW can
-// cache the correct static asset paths.
+// handleManifest serves the pre-computed Web App Manifest.
+func (h *Handler) handleManifest(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/manifest+json")
+	w.Write(h.manifestJSON)
+}
+
+// handleServiceWorker serves the pre-computed service worker JS.
 func (h *Handler) handleServiceWorker(w http.ResponseWriter, r *http.Request) {
-	staticFS, err := fs.Sub(web.StaticFS, "static")
-	if err != nil {
-		http.Error(w, "Not found", http.StatusNotFound)
-		return
-	}
-
-	data, err := fs.ReadFile(staticFS, "sw.js")
-	if err != nil {
-		http.Error(w, "Not found", http.StatusNotFound)
-		return
-	}
-
-	content := strings.ReplaceAll(string(data), "{{BASE_PATH}}", h.deps.Config.BasePath)
-
 	w.Header().Set("Content-Type", "application/javascript")
 	w.Header().Set("Cache-Control", "no-cache")
-	w.Write([]byte(content))
+	w.Write(h.swJS)
 }
 
 // handleShare receives Android share intents via the Web Share Target API
 // and redirects to the new-fave form with pre-filled values.
 // Uses GET to avoid CSRF issues (Android cannot provide CSRF tokens).
 func (h *Handler) handleShare(w http.ResponseWriter, r *http.Request) {
-	user := middleware.UserFromContext(r.Context())
-	if user == nil {
-		http.Redirect(w, r, h.deps.Config.BasePath+"/login", http.StatusSeeOther)
-		return
-	}
-
 	sharedURL := r.URL.Query().Get("url")
 	sharedTitle := r.URL.Query().Get("title")
 	sharedText := r.URL.Query().Get("text")
@@ -88,7 +78,6 @@ func (h *Handler) handleShare(w http.ResponseWriter, r *http.Request) {
 	if sharedURL == "" && sharedText != "" {
 		sharedURL = extractURL(sharedText)
 		if sharedURL != "" {
-			// Remove the URL from text so it's not duplicated.
 			sharedText = strings.TrimSpace(strings.Replace(sharedText, sharedURL, "", 1))
 		}
 	}
@@ -96,7 +85,7 @@ func (h *Handler) handleShare(w http.ResponseWriter, r *http.Request) {
 	description := sharedTitle
 	if description == "" && sharedText != "" {
 		description = sharedText
-		sharedText = "" // Don't duplicate into notes.
+		sharedText = ""
 	}
 
 	target := h.deps.Config.BasePath + "/faves/new?"
@@ -114,7 +103,7 @@ func (h *Handler) handleShare(w http.ResponseWriter, r *http.Request) {
 	http.Redirect(w, r, target+params.Encode(), http.StatusSeeOther)
 }
 
-// handleFaveNewWithPreFill shows the new fave form, optionally pre-filled
+// handleFaveNewPreFill shows the new fave form, optionally pre-filled
 // from query parameters (used by share target and bookmarklets).
 func (h *Handler) handleFaveNewPreFill(w http.ResponseWriter, r *http.Request) {
 	user := middleware.UserFromContext(r.Context())