feat(a4,c3b): complete A-4 Phase 2 agent knowledge migration & Option B isolation removal

- Option B / C-3b: Deprecate isolation.root and remove its 4 legacy consumers in lib.sh, workspace_uuid.py, verify_session.py, and stop_session.sh.
- M2~M7 Migration: Implement artifact_path, verify_artifact, purge_artifacts, spawn_spec, resume_spec, auth_ok, discover, ready_tokens, exit_key, and delegate_agent_key across BaseAgentAdapter and all 4 adapters (Claude, Agy, Hermes, Cline).
- Migrate shell duplications in lib.sh, create_session.sh, resume_session.sh, stop_session.sh, and reconcile.sh to python -m lib_py.agents facts.
- Hardening & Corrections: Fix Cline resume_spec flag to '-i --id', apply shlex.quote across all facts variables with MAM_ prefix, add safe fallback in wait_for_tui_ready.
- Add comprehensive contract tests in tests/test_a4_adapter_contract.py and sync IMPROVEMENTS.md / LOG.md.
- Verified: 100% PASS across unit, component, contract, and integration tests.

.agents/skills/lib_py/atomic_yaml.py

@@ -27,10 +27,6 @@ def atomic_dump_yaml_main():
                 raise SystemExit(f"VALIDATE: herdr_sessions[{i}] {s.get('name')!r} bad status {s['status']!r}")
             if not isinstance(s.get('pane'), dict):
                 raise SystemExit(f"VALIDATE: herdr_sessions[{i}] {s.get('name')!r} missing pane")
-            iso = s.get('isolation')
-            if iso is not None:
-                if not isinstance(iso, dict) or not iso.get('uuid') or not iso.get('root'):
-                    raise SystemExit(f"VALIDATE: herdr_sessions[{i}] {s.get('name')!r} isolation block requires uuid/root")
         orc_uuids = d.get('orchestrator_uuids')
         if orc_uuids is not None:
             if not isinstance(orc_uuids, list):