feat(resume): resume ensures the monitor daemon (Issue #72, decision 2)

Only create started the per-workspace monitor, and only on its job path, so
the stop -> update -> resume flow the update skill requires left no monitor.
resume now calls start_watchdog with the control root as workdir (as create
does since #21 A8, also for a worktree session) after the row is written, on
both the already-running and the spawn path. MAM_NO_SUBSCRIBER_DAEMON=1 starts
none; a failure warns and does not fail the resume.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/data/skill_code_blocks.json

@@ -476,11 +476,11 @@
    "evidence": [
     "multi-agent-mux-resume/scripts/resume_session.sh:111-130",
     "multi-agent-mux-resume/scripts/resume_session.sh:133-144",
-    "multi-agent-mux-resume/scripts/resume_session.sh:147-158",
-    "multi-agent-mux-resume/scripts/resume_session.sh:172-197",
-    "multi-agent-mux-resume/scripts/resume_session.sh:245",
-    "multi-agent-mux-resume/scripts/resume_session.sh:249",
-    "multi-agent-mux-resume/scripts/resume_session.sh:255-258",
+    "multi-agent-mux-resume/scripts/resume_session.sh:147-170",
+    "multi-agent-mux-resume/scripts/resume_session.sh:185-210",
+    "multi-agent-mux-resume/scripts/resume_session.sh:258",
+    "multi-agent-mux-resume/scripts/resume_session.sh:262",
+    "multi-agent-mux-resume/scripts/resume_session.sh:268-271",
     "lib_py/agents/adapters/claude.py:109"
    ],
    "mismatch": [