v3 SQL: walk every source-table reference when pushing dim filters

[shangyian]

Summary

Direct dim-link pushdown in v3 only injects the filter into the primary select of a transform's source body. When the same source table is referenced multiple times (e.g., a pattern where the inner subquery rejoins the source for an FK lookup), the secondary reference is left unfiltered.

There are two pushdown paths in v3:

• Indirect path (dimensions.py's _register_pushdown_into_upstream): runs when the filter resolves via an upstream link rather than a direct one. Uses _resolve_pushdown_targets, which searches through the entire parsed source body and injects into every reference's enclosing select.
• Direct path (cte.py's _resolve_pushdown_filters_for_cte): runs when the parent transform has a direct dim link. Only looks at the CTE's primary select projection and injects into its where clause. Doesn't walk nested subqueries.

Counter-intuitively, adding a direct dim link to a transform makes pushdown less thorough because it short-circuits the upstream path that does the full walk. Modelers see the regression appear when they add what they think is a more-specific link.

The fix is to extend the direct path in cte.py to do the same find_all(ast.Table) walk that the indirect path does. After the primary-select rewrite succeeds.

Test Plan

• PR has an associated issue: #
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• make test shows 100% unit test coverage

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