Skip Values construct in FROM clause instead of raising NotImplementedError

[flipbit03]

Summary

SoftDeleteQueryRewriter.analyze_from() raised NotImplementedError whenever a rewritten SELECT had a SQLAlchemy Values construct (sqlalchemy.values()) as a top-level entry in its FROM clause. A VALUES (...) row set has no underlying table, so there is nothing to soft-delete-filter — it should be skipped (returned unchanged), exactly like the existing TableClause/TextClause branch.

This fix adds a Values branch to analyze_from() that returns the statement unchanged.

Why it matters

Two ways to hit this:

1. Directly — any executed SELECT whose FROM contains a top-level Values.
2. Indirectly (the common real-world trigger) — an ORM bulk UPDATE (update(Model)…) referencing a Values in its WHERE/SET. The library only rewrites SELECTs, but the ORM emits a synchronize-session SELECT to reconcile the identity map, and that spawned SELECT carries the Values in its FROM — so the rewriter tripped on it. The UPDATE t SET col = v.x FROM (VALUES …) AS v WHERE t.id = v.id pattern is a common single-round-trip bulk-update idiom.

Changes

• analyze_from() now returns the statement unchanged for a Values FROM entry (no NotImplementedError).
• Three regression tests in tests/default_config/test_queries.py that execute against the database (PostgreSQL in CI) and assert real behavior:
  • test_select_with_top_level_values_from_is_not_rewritten — a top-level Values SELECT runs and returns its rows.
  • test_orm_update_referencing_values_does_not_trip_rewriter — the ORM UPDATE-with-VALUES executes and the update takes effect.
  • test_table_alongside_values_is_still_soft_delete_filtered — a soft-deletable table alongside a top-level Values still excludes soft-deleted rows (deleted_at IS NULL) while the Values rows pass through.

All three fail on NotImplementedError without the fix and pass with it (verified against PostgreSQL). They skip on SQLite — which only accepts VALUES inside a CTE, not as a top-level FROM — mirroring the existing test_insert_with_returning skip pattern, so the quick make test (SQLite) stays green.

Test plan

• make test-pg (PostgreSQL) → 73 passed
• uv run pytest (SQLite quick) → 3 new tests skip cleanly, rest pass
• ruff check / ruff format --check clean
• mypy clean

Closes #42