ci(greptile): widen guide scope to SQL-bearing non-Python files; fix HAVING-alias wording

Address Greptile review:
- customContext.files scope was **/*.py only, so Query Report SQL in .js/.sql/report .json
  files didn't get the guide attached as context (the global instructions still applied).
  Widen to .py/.js/.sql/report **/*.json.
- The guide's HAVING-alias rule said "with no GROUP BY"; PostgreSQL rejects a SELECT-alias in
  HAVING regardless of GROUP BY. Reworded to match (repeat the expression, or move a
  non-aggregate predicate to WHERE).

.github/POSTGRES_COMPATIBILITY.md

@@ -39,8 +39,9 @@ Flag a changed query that uses any of these:
   `frappe.query_builder.functions` equivalents (`CombineDatetime`, `DateDiff`, `Case`,
   `GroupConcat`, …) or a precomputed column (e.g. `posting_datetime`).
 - **`UPDATE … JOIN`** — not valid on PostgreSQL. Rewrite as `UPDATE … WHERE name IN (subquery)`.
-- **`HAVING` referencing a `SELECT` alias** with no `GROUP BY` — move the predicate into `WHERE`
-  on the underlying expression.
+- **`HAVING` referencing a `SELECT` alias** — PostgreSQL rejects output-column aliases in
+  `HAVING` (regardless of whether the query has a `GROUP BY`; MariaDB allows them). Repeat the
+  underlying expression in `HAVING`, or move a non-aggregate predicate into `WHERE`.
 - **`SELECT DISTINCT … ORDER BY <expr not in the select list>`** — add the expr to the select.
 - **Single-quoted column alias** `AS 'x'` — PostgreSQL reads `'x'` as a string literal. Use an
   unquoted (or double-quoted) alias.