feat(bun): generate native Go array slices for PostgreSQL array columns

Bun's pgdialect scans/appends native slices directly, so array columns
(text[], integer[], uuid[], ...) always generate as plain []string,
[]int32, etc. with an explicit "array" bun tag, regardless of --types
(sqltypes/stdlib/baselib). The SqlXxxArray wrapper types are no longer
used for Bun array columns (gorm is unaffected and keeps using them).

Adds --array-nullable pointer_slice to represent nullable array columns
as *[]T instead of []T, so callers can distinguish SQL NULL (nil) from
'{}' (pointer to an empty slice). Verified end-to-end against a live
PostgreSQL instance for NULL/{}/populated arrays in every --types mode.

Closes #13

vendor/github.com/uptrace/bun/dialect/pgdialect/parser.go

@@ -0,0 +1,143 @@
+package pgdialect
+
+import (
+	"bytes"
+	"encoding/hex"
+
+	"github.com/uptrace/bun/internal/parser"
+)
+
+type pgparser struct {
+	parser.Parser
+	buf []byte
+}
+
+func newParser(b []byte) *pgparser {
+	p := new(pgparser)
+	p.Reset(b)
+	return p
+}
+
+func (p *pgparser) ReadLiteral(ch byte) []byte {
+	p.Unread()
+	lit, _ := p.ReadSep(',')
+	return lit
+}
+
+func (p *pgparser) ReadUnescapedSubstring(ch byte) ([]byte, error) {
+	return p.readSubstring(ch, false)
+}
+
+func (p *pgparser) ReadSubstring(ch byte) ([]byte, error) {
+	return p.readSubstring(ch, true)
+}
+
+func (p *pgparser) readSubstring(ch byte, escaped bool) ([]byte, error) {
+	ch, err := p.ReadByte()
+	if err != nil {
+		return nil, err
+	}
+
+	p.buf = p.buf[:0]
+	for {
+		if ch == '"' {
+			break
+		}
+
+		next, err := p.ReadByte()
+		if err != nil {
+			return nil, err
+		}
+
+		if ch == '\\' {
+			switch next {
+			case '\\', '"':
+				p.buf = append(p.buf, next)
+
+				ch, err = p.ReadByte()
+				if err != nil {
+					return nil, err
+				}
+			default:
+				p.buf = append(p.buf, '\\')
+				ch = next
+			}
+			continue
+		}
+
+		if escaped && ch == '\'' && next == '\'' {
+			p.buf = append(p.buf, next)
+			ch, err = p.ReadByte()
+			if err != nil {
+				return nil, err
+			}
+			continue
+		}
+
+		p.buf = append(p.buf, ch)
+		ch = next
+	}
+
+	if bytes.HasPrefix(p.buf, []byte("\\x")) && len(p.buf)%2 == 0 {
+		data := p.buf[2:]
+		buf := make([]byte, hex.DecodedLen(len(data)))
+		n, err := hex.Decode(buf, data)
+		if err != nil {
+			return nil, err
+		}
+		return buf[:n], nil
+	}
+
+	return p.buf, nil
+}
+
+func (p *pgparser) ReadRange(ch byte) ([]byte, error) {
+	p.buf = p.buf[:0]
+	p.buf = append(p.buf, ch)
+
+	for p.Valid() {
+		ch = p.Read()
+		p.buf = append(p.buf, ch)
+		if ch == ']' || ch == ')' {
+			break
+		}
+	}
+
+	return p.buf, nil
+}
+
+func (p *pgparser) ReadJSON() ([]byte, error) {
+	p.Unread()
+
+	c, err := p.ReadByte()
+	if err != nil {
+		return nil, err
+	}
+
+	p.buf = p.buf[:0]
+
+	depth := 0
+	for {
+		switch c {
+		case '{':
+			depth++
+		case '}':
+			depth--
+		}
+
+		p.buf = append(p.buf, c)
+
+		if depth == 0 {
+			break
+		}
+
+		next, err := p.ReadByte()
+		if err != nil {
+			return nil, err
+		}
+
+		c = next
+	}
+
+	return p.buf, nil
+}