Close HUB-WP-0009 conformance gaps (C2, C7, C9, C10); mark blocked workplans

Implements the four residual conformance checks left open by the T04
minimal vertical:

- C2: GET /ports/registry/registrations/{hub_slug} resolves missing (404),
  ambiguous (shared reuse_surface_id across hub_slugs), and stale
  (deprecated/retired descriptor) registrations; a new .../audit route
  exposes queryable registration history from the existing in-memory
  history and the PostgreSQL runtime_audit_ledger.
- C7: harness proof that disabled compatibility groups deny access
  (404) with no fixture credentials involved, matching the existing
  fail-closed compat router behavior.
- C9: harness proof plus a dedicated test that /readyz degrades only on
  an unavailable configured dependency while unrelated disabled
  projections stay non-blocking.
- C10: ContractValidator now negotiates contract_version_min/max against
  the runtime's contract version and rejects incompatible or inverted
  ranges with an explicit 422 instead of silently accepting them.

HUB-WP-0009 is now finished. HUB-WP-0006 is marked blocked: its only open
task (T06) has no remaining hub-core code path and waits on an external
Forgejo identity/production deployment gate. HUB-WP-0011 is marked
blocked: T02/T03 already waited on external credential/deployment
review, and T01 needs a source/destination ownership and retention
decision against live message data before it can be implemented safely.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Assistant: claude-code
Assistant-Model: sonnet
Assistant-Process: 310936@bnt-lap001
Assistant-Session: 00cd9abe-09a0-416b-88e0-f907b9101629

tests/test_conformance.py

@@ -18,19 +18,23 @@ def test_implemented_tier_2_and_3_profile_passes_reference_runtime() -> None:
     report = ConformanceHarness(isolated_target()).run()
 
     assert report.passed
-    assert report.passed_count == 8
+    assert report.passed_count == 12
     assert {check.check_id for check in report.checks} == {
         "C1",
+        "C2",
         "C3",
         "C4",
         "C5",
         "C6",
+        "C7",
         "C8",
+        "C9",
+        "C10",
         "F2",
         "F3",
     }
     assert all(check.status == "pass" for check in report.checks)
-    assert report.to_dict()["summary"] == {"passed": 8, "total": 8}
+    assert report.to_dict()["summary"] == {"passed": 12, "total": 12}
 
 
 def test_projection_rebuild_scenario_leaves_separate_provenance_bearing_views() -> None: