Handle TEMPORARY keyword in EXISTS and SHOW statements

Add Temporary field to ExistsQuery and ShowQuery AST types.
Parse TEMPORARY keyword in:
- EXISTS TEMPORARY TABLE statements
- SHOW TEMPORARY TABLES statements

Fixes 5 statements across 2 tests:
- 00564_temporary_table_management (3 statements)
- 00492_drop_temporary_table (2 statements)

Author: claude

ast/ast.go

@@ -775,6 +775,7 @@ func (d *DescribeQuery) statementNode()      {}
 type ShowQuery struct {
 	Position      token.Position `json:"-"`
 	ShowType      ShowType       `json:"show_type"`
+	Temporary     bool           `json:"temporary,omitempty"`
 	Database      string         `json:"database,omitempty"`
 	From          string         `json:"from,omitempty"`
 	Like          string         `json:"like,omitempty"`
@@ -956,6 +957,7 @@ const (
 type ExistsQuery struct {
 	Position   token.Position `json:"-"`
 	ExistsType ExistsType     `json:"exists_type,omitempty"`
+	Temporary  bool           `json:"temporary,omitempty"`
 	Database   string         `json:"database,omitempty"`
 	Table      string         `json:"table"`
 	Settings   []*SettingExpr `json:"settings,omitempty"`

parser/parser.go

@@ -5862,6 +5862,12 @@ func (p *Parser) parseShow() ast.Statement {
 		Position: pos,
 	}
 
+	// Handle TEMPORARY keyword (SHOW TEMPORARY TABLES)
+	if p.currentIs(token.TEMPORARY) {
+		show.Temporary = true
+		p.nextToken()
+	}
+
 	switch p.current.Token {
 	case token.TABLES:
 		show.ShowType = ast.ShowTables
@@ -7192,6 +7198,12 @@ func (p *Parser) parseExistsStatement() *ast.ExistsQuery {
 
 	p.nextToken() // skip EXISTS
 
+	// Check for TEMPORARY keyword
+	if p.currentIs(token.TEMPORARY) {
+		exists.Temporary = true
+		p.nextToken()
+	}
+
 	// Check for DICTIONARY, DATABASE, VIEW, or TABLE keyword
 	if p.currentIs(token.TABLE) {
 		exists.ExistsType = ast.ExistsTable

parser/testdata/00492_drop_temporary_table/metadata.json

@@ -1,6 +1 @@
-{
-  "explain_todo": {
-    "stmt6": true,
-    "stmt8": true
-  }
-}
+{}

parser/testdata/00564_temporary_table_management/metadata.json

@@ -1,7 +1,2 @@
 {
-  "explain_todo": {
-    "stmt3": true,
-    "stmt5": true,
-    "stmt7": true
-  }
 }