Handle FROM (SELECT...) as clause keyword after trailing comma

When parsing column list with trailing comma, recognize FROM (SELECT...)
and FROM (WITH...) as FROM clause with subquery, not as a function call.
This fixes parsing of queries like:
  SELECT x, count(), FROM (SELECT ...)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: kyleconroy

parser/expression.go

@@ -185,8 +185,16 @@ func (p *Parser) isClauseKeyword() bool {
 	case token.RPAREN, token.SEMICOLON, token.EOF:
 		return true
 	// FROM is a clause keyword unless followed by ( or [ (function/index access)
+	// Exception: FROM (SELECT ...) or FROM (WITH ...) is a subquery, not a function call
 	case token.FROM:
-		return !p.peekIs(token.LPAREN) && !p.peekIs(token.LBRACKET)
+		if p.peekIs(token.LPAREN) {
+			// Check if it's FROM (SELECT...) or FROM (WITH...) - that's a subquery
+			if p.peekPeekIs(token.SELECT) || p.peekPeekIs(token.WITH) {
+				return true
+			}
+			return false
+		}
+		return !p.peekIs(token.LBRACKET)
 	// These keywords can be used as identifiers in ClickHouse
 	// Only treat as clause keywords if NOT followed by expression-like tokens
 	case token.WHERE, token.GROUP, token.HAVING, token.ORDER, token.LIMIT:

parser/testdata/03151_external_cross_join/metadata.json

@@ -1,5 +1 @@
-{
-  "explain_todo": {
-    "stmt8": true
-  }
-}
+{}

parser/testdata/03262_filter_push_down_view/metadata.json

@@ -1,5 +1 @@
-{
-  "explain_todo": {
-    "stmt5": true
-  }
-}
+{}