feat(sql): add COMMENT keyword completion

apps/desktop/src/lib/sql/sqlCompletion.ts

@@ -382,6 +382,7 @@ const COMMON_SQL_KEYWORDS = [
 ];
 
 const POSTGRES_SQL_KEYWORDS = [
+  "COMMENT",
   "BIGSERIAL",
   "JSON",
   "JSONB",
@@ -415,6 +416,7 @@ const POSTGRES_SQL_KEYWORDS = [
 
 const MYSQL_SQL_KEYWORDS = [
   "AUTO_INCREMENT",
+  "COMMENT",
   "UNSIGNED",
   "ZEROFILL",
   "ENGINE",
@@ -577,6 +579,15 @@ const DATABASE_SQL_KEYWORDS: Partial<Record<DatabaseType, string[]>> = {
   oracle: ORACLE_SQL_KEYWORDS,
   "oceanbase-oracle": ORACLE_SQL_KEYWORDS,
   manticoresearch: MANTICORESEARCH_SQL_KEYWORDS,
+  duckdb: ["COMMENT"],
+  clickhouse: ["COMMENT"],
+  doris: ["COMMENT"],
+  starrocks: ["COMMENT"],
+  dameng: ["COMMENT"],
+  kingbase: ["COMMENT"],
+  vastbase: ["COMMENT"],
+  spark: ["COMMENT"],
+  iotdb: ["COMMENT"],
 };
 
 // Keywords that appear in nearly every SQL query — boosted so frequency beats length tie-breaking.
@@ -640,6 +651,7 @@ const DDL_ONLY_KEYWORDS = new Set([
   "CREATE",
   "ALTER",
   "DROP",
+  "COMMENT",
   "TABLE",
   "VIEW",
   "INDEX",