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

vendor/github.com/jackc/pgx/v5/pgproto3/gss_response.go

@@ -0,0 +1,46 @@
+package pgproto3
+
+import (
+	"encoding/json"
+)
+
+type GSSResponse struct {
+	Data []byte
+}
+
+// Frontend identifies this message as sendable by a PostgreSQL frontend.
+func (g *GSSResponse) Frontend() {}
+
+func (g *GSSResponse) Decode(data []byte) error {
+	g.Data = data
+	return nil
+}
+
+func (g *GSSResponse) Encode(dst []byte) ([]byte, error) {
+	dst, sp := beginMessage(dst, 'p')
+	dst = append(dst, g.Data...)
+	return finishMessage(dst, sp)
+}
+
+// MarshalJSON implements encoding/json.Marshaler.
+func (g *GSSResponse) MarshalJSON() ([]byte, error) {
+	return json.Marshal(struct {
+		Type string
+		Data []byte
+	}{
+		Type: "GSSResponse",
+		Data: g.Data,
+	})
+}
+
+// UnmarshalJSON implements encoding/json.Unmarshaler.
+func (g *GSSResponse) UnmarshalJSON(data []byte) error {
+	var msg struct {
+		Data []byte
+	}
+	if err := json.Unmarshal(data, &msg); err != nil {
+		return err
+	}
+	g.Data = msg.Data
+	return nil
+}