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/big_endian.go

@@ -0,0 +1,37 @@
+package pgproto3
+
+import (
+	"encoding/binary"
+)
+
+type BigEndianBuf [8]byte
+
+func (b BigEndianBuf) Int16(n int16) []byte {
+	buf := b[0:2]
+	binary.BigEndian.PutUint16(buf, uint16(n))
+	return buf
+}
+
+func (b BigEndianBuf) Uint16(n uint16) []byte {
+	buf := b[0:2]
+	binary.BigEndian.PutUint16(buf, n)
+	return buf
+}
+
+func (b BigEndianBuf) Int32(n int32) []byte {
+	buf := b[0:4]
+	binary.BigEndian.PutUint32(buf, uint32(n))
+	return buf
+}
+
+func (b BigEndianBuf) Uint32(n uint32) []byte {
+	buf := b[0:4]
+	binary.BigEndian.PutUint32(buf, n)
+	return buf
+}
+
+func (b BigEndianBuf) Int64(n int64) []byte {
+	buf := b[0:8]
+	binary.BigEndian.PutUint64(buf, uint64(n))
+	return buf
+}