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/elem.go

@@ -0,0 +1,87 @@
+package pgdialect
+
+import (
+	"database/sql/driver"
+	"encoding/hex"
+	"fmt"
+	"strconv"
+	"time"
+	"unicode/utf8"
+
+	"github.com/uptrace/bun/dialect"
+)
+
+func appendElem(buf []byte, val any) []byte {
+	switch val := val.(type) {
+	case int64:
+		return strconv.AppendInt(buf, val, 10)
+	case float64:
+		return arrayAppendFloat64(buf, val)
+	case bool:
+		return dialect.AppendBool(buf, val)
+	case []byte:
+		return appendBytesElem(buf, val)
+	case string:
+		return appendStringElem(buf, val)
+	case time.Time:
+		buf = append(buf, '"')
+		buf = appendTime(buf, val)
+		buf = append(buf, '"')
+		return buf
+	case driver.Valuer:
+		val2, err := val.Value()
+		if err != nil {
+			err := fmt.Errorf("pgdialect: can't append elem value: %w", err)
+			return dialect.AppendError(buf, err)
+		}
+		return appendElem(buf, val2)
+	default:
+		err := fmt.Errorf("pgdialect: can't append elem %T", val)
+		return dialect.AppendError(buf, err)
+	}
+}
+
+func appendBytesElem(b []byte, bs []byte) []byte {
+	if bs == nil {
+		return dialect.AppendNull(b)
+	}
+
+	b = append(b, `"\\x`...)
+
+	s := len(b)
+	b = append(b, make([]byte, hex.EncodedLen(len(bs)))...)
+	hex.Encode(b[s:], bs)
+
+	b = append(b, '"')
+
+	return b
+}
+
+func appendStringElem(b []byte, s string) []byte {
+	b = append(b, '"')
+	for _, r := range s {
+		switch r {
+		case 0:
+			// ignore
+		case '\'':
+			b = append(b, "''"...)
+		case '"':
+			b = append(b, '\\', '"')
+		case '\\':
+			b = append(b, '\\', '\\')
+		default:
+			if r < utf8.RuneSelf {
+				b = append(b, byte(r))
+				break
+			}
+			l := len(b)
+			if cap(b)-l < utf8.UTFMax {
+				b = append(b, make([]byte, utf8.UTFMax)...)
+			}
+			n := utf8.EncodeRune(b[l:l+utf8.UTFMax], r)
+			b = b[:l+n]
+		}
+	}
+	b = append(b, '"')
+	return b
+}