chore: add .custodian-brief.md protocol and unblock T07

- CLAUDE.md: read .custodian-brief.md as Step 1 (offline-safe orientation
  before MCP call); matches pattern now standard across all domain repos
- T07 (Smoke test Temporal): remove stale Docker TLS blocking_reason;
  status → todo (WSL2 MTU issue resolved by implementing on CoulombCore)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

CLAUDE.md

@@ -40,13 +40,19 @@ exposes tools for reading and writing state without touching the API directly.
 **On receiving your first message — before writing any response text — execute
 this orientation sequence. Do not greet, do not ask what to do first.**
 
-**Step 1 — Call the State Hub**
+**Step 1 — Read the offline-safe brief**
+```bash
+cat .custodian-brief.md
+```
+This always works — no MCP, no network required.
+
+**Step 1b — Call the State Hub for richer context** (skip if MCP unreachable)
 ```
 get_domain_summary("custodian")   # workstreams, blocking decisions, recent progress, SBOM status
 ```
 If the call fails, the API is offline: `cd ~/the-custodian/state-hub && make api`
 
-**Step 1b — Check the agent inbox**
+**Step 1c — Check the agent inbox**
 ```
 get_messages(to_agent="activity-core", unread_only=True)
 ```