Initial lookbook implementation

Pinterest-style visual bookmarking app with:
- URL metadata extraction (OG/Twitter meta, oEmbed fallback)
- Image caching in Postgres with 480px thumbnails
- Multi-tag filtering with Ctrl/Cmd for OR mode
- Fuzzy tag suggestions and inline tag editing
- Browser console auth() with first-use password setup
- Brutalist UI with Commit Mono font and Pico CSS
- Light/dark mode via browser preference

internal/handlers/router.go

@@ -0,0 +1,42 @@
+package handlers
+
+import (
+	"net/http"
+)
+
+// Router wraps http.ServeMux and automatically injects RequestContext into handlers.
+type Router struct {
+	mux *http.ServeMux
+	rc  *RequestContext
+}
+
+func NewRouter(rc *RequestContext) *Router {
+	return &Router{
+		mux: http.NewServeMux(),
+		rc:  rc,
+	}
+}
+
+// Handle registers a handler that returns an error.
+// The RequestContext is automatically injected and error handling is applied.
+func (rt *Router) Handle(pattern string, h Handler) {
+	rt.mux.HandleFunc(pattern, func(w http.ResponseWriter, r *http.Request) {
+		rc := &RequestContext{
+			DB:        rt.rc.DB,
+			Logger:    rt.rc.Logger,
+			TmplCache: rt.rc.TmplCache,
+		}
+
+		handler := WithErrorHandling(rc, h)
+		handler(w, r)
+	})
+}
+
+// HandleStd registers a standard http.Handler (for static files, etc.)
+func (rt *Router) HandleStd(pattern string, h http.Handler) {
+	rt.mux.Handle(pattern, h)
+}
+
+func (rt *Router) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	rt.mux.ServeHTTP(w, r)
+}