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/copy_fail.go

@@ -0,0 +1,45 @@
+package pgproto3
+
+import (
+	"bytes"
+	"encoding/json"
+)
+
+type CopyFail struct {
+	Message string
+}
+
+// Frontend identifies this message as sendable by a PostgreSQL frontend.
+func (*CopyFail) Frontend() {}
+
+// 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 *CopyFail) Decode(src []byte) error {
+	idx := bytes.IndexByte(src, 0)
+	if idx != len(src)-1 {
+		return &invalidMessageFormatErr{messageType: "CopyFail"}
+	}
+
+	dst.Message = string(src[:idx])
+
+	return nil
+}
+
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
+func (src *CopyFail) Encode(dst []byte) ([]byte, error) {
+	dst, sp := beginMessage(dst, 'f')
+	dst = append(dst, src.Message...)
+	dst = append(dst, 0)
+	return finishMessage(dst, sp)
+}
+
+// MarshalJSON implements encoding/json.Marshaler.
+func (src CopyFail) MarshalJSON() ([]byte, error) {
+	return json.Marshal(struct {
+		Type    string
+		Message string
+	}{
+		Type:    "CopyFail",
+		Message: src.Message,
+	})
+}