Delete retired approval detection and manager routes

[shiny-code-app]

Refs #2525.

Retired approval services were still imported by live Launchplane paths. This removes the change-impact classifier, Product Owner policy service, manager approval commands/projection, and their HTTP routes. Merge admission now uses an independent Git evidence reader, while the configured signed webhook transport continues to capture trusted-maintenance evidence.

New engineering decisions use the first two configured independent review slots without consulting path-based approval policies. Historical record contracts and digests remain readable, and current product Owner/release review remains covered by regression tests. Public API artifacts and operational docs reflect the removed routes. The diff is mostly deletion, mechanical import moves, and generated schema changes; keeping the callers together avoids an intermediate broken service.

Validation at a8aa8b0013ad9596b3e0f628192e3fe2ff20daf6:

• All 33 GitHub checks are terminal without failures, including PostgreSQL integration, browser smoke, CodeQL, security and unit-test shards. No CI reruns were needed.
• All 12 local unittest shards pass for the deletion; 83 affected tests pass after the final inspection cleanups.
• Ruff lint/format, mypy across 1,035 source files, and frontend validation (75 tests, API drift, typecheck, production build) pass.
• Anthropic claude-opus-5-5 reviewed both the deletion and the final cleanup delta; neither review found an actionable correctness or contract regression.
• PyCharm captured all 1,165 findings across the 53 changed Python files before cleanup. Nine overlapped changed lines: eight were fixed; the retained duplicate-validator warning keeps live evidence independent from frozen historical approval contracts. The final seven-file rerun collected 48 findings (29 warnings, 19 weak warnings, no errors), with only that intentional duplicate on changed lines. It has no coverage-proof gap and cleanup left the worktree unchanged. The other 47 locations are unchanged. The broad source capture retained execution_not_proven, and whole-project attempts timed out; no whole-project clean result is claimed. The owner's decision in Triage IDE diagnostics in existing Launchplane files #2463 ended baseline cleanup, so it is not reopened here. Full private captures and location triage were copied into an owner-only local archive and hash-verified before retiring the completed task worktree.

Background Review: not yet observable for a8aa8b0013ad9596b3e0f628192e3fe2ff20daf6 as of 2026-09-27 18:56 UTC; a post-turn review may still start. The PR has no unanswered external comments. Launchplane landed this PR at de7f3abb2b8a63ddb465e59e239f86b4ba8db3c1. Post-merge CI, Security, CodeQL, and deployment all passed. Deployed smoke verified the matching image, healthy service, compatible database revision, and representative native routes. Local main is clean at the landing SHA.

Compatibility: existing database rows and immutable digests are preserved. New schema-version-2 engineering decisions require a compatible reader; a rollback image that only understands version 1 must not be assumed able to read newly written decisions. Runtime grant and credential contraction is outside this code deletion. The CM delivery hold remains in force.

Owner test notes

Nothing for the site Owner to test. This is control-plane retirement; current preview/release review and release blocking are exercised by automated tests.

Closeout (2026-09-27 19:47 UTC): #2525 is complete. The task worktree, merged local branch, and 72 task scratch files are removed; 175 retained evidence/configuration files were verified before removal. The remote task branch was already absent. Local main remains clean at the deployed landing SHA; other worktrees, refs, stashes, and shared caches were preserved. Background Review remains not yet observable for source head a8aa8b0013ad9596b3e0f628192e3fe2ff20daf6 at this observation; a post-turn review may still start.

Final IDE cleanup: the obsolete task-specific PyCharm interpreter reference was removed through the IDE UI. Other interpreter entries were preserved, and the active project retained its original interpreter.