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/authentication_ok.go

@@ -0,0 +1,50 @@
+package pgproto3
+
+import (
+	"encoding/binary"
+	"encoding/json"
+	"errors"
+
+	"github.com/jackc/pgx/v5/internal/pgio"
+)
+
+// AuthenticationOk is a message sent from the backend indicating that authentication was successful.
+type AuthenticationOk struct{}
+
+// Backend identifies this message as sendable by the PostgreSQL backend.
+func (*AuthenticationOk) Backend() {}
+
+// Backend identifies this message as an authentication response.
+func (*AuthenticationOk) AuthenticationResponse() {}
+
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
+func (dst *AuthenticationOk) Decode(src []byte) error {
+	if len(src) != 4 {
+		return errors.New("bad authentication message size")
+	}
+
+	authType := binary.BigEndian.Uint32(src)
+
+	if authType != AuthTypeOk {
+		return errors.New("bad auth type")
+	}
+
+	return nil
+}
+
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
+func (src *AuthenticationOk) Encode(dst []byte) ([]byte, error) {
+	dst, sp := beginMessage(dst, 'R')
+	dst = pgio.AppendUint32(dst, AuthTypeOk)
+	return finishMessage(dst, sp)
+}
+
+// MarshalJSON implements encoding/json.Marshaler.
+func (src AuthenticationOk) MarshalJSON() ([]byte, error) {
+	return json.Marshal(struct {
+		Type string
+	}{
+		Type: "AuthenticationOK",
+	})
+}