Prepare stable 2.5.12 original query timeout correction

[rmcdaniel]

Backport #144 onto exact published 2.5.11 as a separately qualified 2.5.12 candidate. A canonical query timeout now reaches the caller with its original typed response, rather than triggering a distinct query admission through HTTP retries. Unrelated transport retries keep their existing behavior.

Normally installed exact candidate wheel passes 239 client/retry tests, including default 1.20 and explicit 1.19 discovery plus namespaced/control routes. The twelve canonical-timeout controls fail against normally installed 2.5.11. A separate immutable Server 2.6.1 HTTP control is being qualified; the original observer setup failure stopped before API admission, was retained, and its resources were immediately retired.

Full final source/stable gates, actual HTTP control and published installation are required before publication. The unchanged published 2.5.11 identity and frozen consumer/cohort tuples remain intact. Pending main Nexus producer work is excluded. Query hydration/authority remains open in #143, with the actual Server timing/status contract separately owned in Server #433. Refs #143; source #144.

[rmcdaniel]

Complete source CI 38343855047 passes at 3256e2a79ede12b9d71f26e50a4a80dc88d4978c. The normally installed compatible stable candidate passes 239 client/retry tests; all twelve canonical-timeout Client regressions fail published 2.5.11. Ruff and mypy pass, and the corpus guard/history fixtures remain unchanged.

Four actual HTTP controls on unchanged immutable Server 2.6.1 / MySQL / Redis pass with default 1.20 and explicit minimum 1.19. Each starts its own synthetic workflow; the isolated control's query/lease limits are 3/8 seconds, independent of every original failed reference and its deadlines. Published 2.5.11 sends three slow-query POSTs and exposes the final failure after 9.66–9.82 seconds. The candidate sends one, exposes the first original query_worker_execution_timeout / 504 body after 3.19 seconds, and preserves that response exactly. Each control also executes an ordinary fast query returning 7. Real leased query identities and typed late-completion fences are retained.

The first observer setup failed before discovery/admission and its stack was immediately retired. Fresh corrected controls use a separate stack. All runtime/control containers, networks and database volumes are now retired, before the original 04:15 cutoff.

This qualifies the caller retry correction. Query hydration/lease authority remains open in #143, and Server #433 owns the actual timing/status boundary. No Source600 retrospective cause, original deadline extension, frozen retuple or new Nexus capability is inferred. Stable #145 and registry verification remain separate gates.