fix: task_insert() uses INSERT ... AS alias unsupported before 9.5

INSERT INTO tablename AS alias was added in PostgreSQL 9.5 alongside
ON CONFLICT; on 9.4 it's a plain syntax error, so every repeat-chain
insert failed there ("syntax error at or near AS"), crashing the
owning pg_work worker and looping it through the 60s bgw_restart_time
throttle - confirmed via debug log from CI run 30324794582's
REL9_4_STABLE-test job. The "AS t" alias on the INSERT target was
never needed (only RETURNING t.id used it); drop it and return
RETURNING id instead, which is valid on every supported version.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Author: RekGRpth

task.c

@@ -100,9 +100,9 @@ static void task_insert(const Task *t) {
         if (!columns) return;
         initStringInfoMy(&src);
         appendStringInfo(&src, SQL(
-            WITH s AS (SELECT * FROM %1$s AS t WHERE "id" OPERATOR(pg_catalog.=) $1 FOR UPDATE OF t) INSERT INTO %1$s AS t ("parent", "plan", %2$s) SELECT "id", CASE
+            WITH s AS (SELECT * FROM %1$s AS t WHERE "id" OPERATOR(pg_catalog.=) $1 FOR UPDATE OF t) INSERT INTO %1$s ("parent", "plan", %2$s) SELECT "id", CASE
                 WHEN "drift" THEN %3$s OPERATOR(pg_catalog.+) "repeat" ELSE (WITH RECURSIVE r AS (SELECT "plan" AS p UNION SELECT p OPERATOR(pg_catalog.+) "repeat" FROM r WHERE p OPERATOR(pg_catalog.<=) %3$s) SELECT * FROM r ORDER BY 1 DESC LIMIT 1)
-            END AS "plan", %2$s FROM s WHERE "repeat" OPERATOR(pg_catalog.>) '0 sec' LIMIT 1 RETURNING t.id
+            END AS "plan", %2$s FROM s WHERE "repeat" OPERATOR(pg_catalog.>) '0 sec' LIMIT 1 RETURNING id
         ), t->work->schema_table, columns, init_plan());
         pfree(columns);
     }