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/startup_message.go

@@ -0,0 +1,94 @@
+package pgproto3
+
+import (
+	"bytes"
+	"encoding/binary"
+	"encoding/json"
+	"errors"
+	"fmt"
+
+	"github.com/jackc/pgx/v5/internal/pgio"
+)
+
+const ProtocolVersionNumber = 196608 // 3.0
+
+type StartupMessage struct {
+	ProtocolVersion uint32
+	Parameters      map[string]string
+}
+
+// Frontend identifies this message as sendable by a PostgreSQL frontend.
+func (*StartupMessage) 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 *StartupMessage) Decode(src []byte) error {
+	if len(src) < 4 {
+		return errors.New("startup message too short")
+	}
+
+	dst.ProtocolVersion = binary.BigEndian.Uint32(src)
+	rp := 4
+
+	if dst.ProtocolVersion != ProtocolVersionNumber {
+		return fmt.Errorf("Bad startup message version number. Expected %d, got %d", ProtocolVersionNumber, dst.ProtocolVersion)
+	}
+
+	dst.Parameters = make(map[string]string)
+	for {
+		idx := bytes.IndexByte(src[rp:], 0)
+		if idx < 0 {
+			return &invalidMessageFormatErr{messageType: "StartupMessage"}
+		}
+		key := string(src[rp : rp+idx])
+		rp += idx + 1
+
+		idx = bytes.IndexByte(src[rp:], 0)
+		if idx < 0 {
+			return &invalidMessageFormatErr{messageType: "StartupMessage"}
+		}
+		value := string(src[rp : rp+idx])
+		rp += idx + 1
+
+		dst.Parameters[key] = value
+
+		if len(src[rp:]) == 1 {
+			if src[rp] != 0 {
+				return fmt.Errorf("Bad startup message last byte. Expected 0, got %d", src[rp])
+			}
+			break
+		}
+	}
+
+	return nil
+}
+
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
+func (src *StartupMessage) Encode(dst []byte) ([]byte, error) {
+	sp := len(dst)
+	dst = pgio.AppendInt32(dst, -1)
+
+	dst = pgio.AppendUint32(dst, src.ProtocolVersion)
+	for k, v := range src.Parameters {
+		dst = append(dst, k...)
+		dst = append(dst, 0)
+		dst = append(dst, v...)
+		dst = append(dst, 0)
+	}
+	dst = append(dst, 0)
+
+	return finishMessage(dst, sp)
+}
+
+// MarshalJSON implements encoding/json.Marshaler.
+func (src StartupMessage) MarshalJSON() ([]byte, error) {
+	return json.Marshal(struct {
+		Type            string
+		ProtocolVersion uint32
+		Parameters      map[string]string
+	}{
+		Type:            "StartupMessage",
+		ProtocolVersion: src.ProtocolVersion,
+		Parameters:      src.Parameters,
+	})
+}