chore(p0): retire regress, the skill router, the module audit tool and vocabulary.sc

Off every active line (PATHFINDER-2026-10-13/03-unified-proposal.md, cuts).
Deleted: src/openultrasast/regress/ and the deep-mode REGRESS branch (deep
now records a regress_retired degradation and equals standard; proof is the
search-with-proof arm's job), the sandbox docker runner and probe that only
regress used, --fail-on worth-fixing, RegressConfig, the two ledger helpers
only regress called; skills.py and index.py with the hunter pool's skill
routing; model/audit.py; cpg/queries/vocabulary.sc with
benchmarks/push/ontology_gap.py. Docs and the scan skill describe the
retirement. Net: 3,895 lines deleted, 86 added. Targeted tests: 180 passed,
28 skipped; 3,331 tests collect.

Co-Authored-By: Claude Fable 5.1 <[email protected]>

src/openultrasast/sandbox/__init__.py

@@ -1,25 +1,5 @@
-"""Isolated Docker CLI sandbox."""
+"""Shared sandbox job and result types."""
 
-from .probe import FakeSandboxProbe, SandboxProbe, resolve_sandbox_probe
-from .runner import (
-    DockerCliRunner,
-    FakeSandboxRunner,
-    SandboxJob,
-    SandboxResult,
-    SandboxRunner,
-    build_docker_argv,
-    resolve_sandbox_runner,
-)
+from .runner import SandboxJob, SandboxResult
 
-__all__ = [
-    "DockerCliRunner",
-    "FakeSandboxProbe",
-    "FakeSandboxRunner",
-    "SandboxJob",
-    "SandboxProbe",
-    "SandboxResult",
-    "SandboxRunner",
-    "build_docker_argv",
-    "resolve_sandbox_probe",
-    "resolve_sandbox_runner",
-]
+__all__ = ["SandboxJob", "SandboxResult"]