HogQL rejects a WITH alias that references a column of the queried table

Bug description

ClickHouse accepts a scalar WITH alias whose expression references columns of the table in
FROM:

WITH toStartOfDay(timestamp) AS day
SELECT day, count()
FROM events
GROUP BY day

HogQL raises No scope or CTE available instead, because the WITH clause is resolved before
the query scope exists.

Mechanism

In posthog/hogql/resolver.py, visit_select_query begins at line 881:

• line 897 — "First step: resolve all the WITH CTEs onto self.ctes"
• line 923 — node.select_from is first visited

So a WITH expression is resolved 26 lines before anything knows what FROM contains. On a
top-level query there is neither an enclosing scope nor a CTE to fall back to, and the lookup
reaches posthog/hogql/resolver.py:2697:

raise QueryError("No scope or CTE available")

Suggested direction

Split the two kinds of WITH entry rather than resolving them in one pass:

• subquery CTEs must resolve first, because FROM may reference them
• expression CTEs can resolve after select_from, where a scope exists

The Rust parser should be checked for the same ordering, so the two do not diverge.

Notes

Traced in the code on master today. Not executed — a resolver-level repro needs a database
context, which needs a running Postgres.

Start in posthog/hogql/resolver.py at visit_select_query around lines 881-923 and inspect the lookup at line 2697. Reproduce the scalar WITH alias against a table-backed query with a running Postgres database, then verify subquery CTEs still resolve before FROM while expression CTEs resolve after select_from. Check the Rust parser for matching ordering and confirm both implementations behave consistently.