Client hook/form parity: react/tanstack emit hooks for objects whose routes no longer exist

[dmealing]

Follow-up from #248 (PR #249), design spec §9c.

codegen-ts-react / codegen-ts-tanstack emit hooks/forms for any object (compilable today — they bind types/schemas that ARE emitted). After #248, queries/routes stop being emitted for a sourceless object, so any generated hook that fetches through those routes now dangles at runtime.

Align the client-side generator filters with hasAnyRdbSource (exported from @metaobjectsdev/codegen-ts as of #248) so hooks/forms are only emitted for objects that actually have a DB-backed API surface. Ergonomics follow-up, not a correctness bug (the generated code still typechecks). Ref: §9c.

[dmealing]

Closing — not tracking as a separate issue. This deferred item remains documented in the #248 design spec (docs/superpowers/specs/2026-08-01-issue-248-persistability-from-source-design.md §9) on main.