Add framework design docs (model-divergence, rule agents, agent tab)

Design docs in design/framework/ covering:
- Model-divergence enforcement (conflict matrix, modes, auto-assignment)
- Rule Proposer agent (daily scan, proposes rules to RULE_PROPOSALS.md)
- Rule Reviewer agent (monthly consolidation, different LLM than Proposer)
- Agent tab redesign (phase roles + scheduled jobs, remove fake types)
- Schedules, conflict-of-interest, success criteria

Cross-references updated in AGENTS.md, README.md, CHANGELOG.md,
.onboarding.md, prompts/onboarding.md, design/loops/{README,BACKLOG}.md,
memory/v1-1-hardening-session.md.

Also restores scripts/automaton-cleanup.sh stub (was corrupted by
pytest test leak writing temp path into real stub).

prompts/onboarding.md

@@ -75,6 +75,13 @@ Install the automaton pre-commit hook to block commits when no task is in an edi
 4. Verify the hook: `python ~/.automaton/scripts/status.py --can-edit --project {project}` should return exit code 1 (DENIED) since no tasks exist yet.
 5. Note in the onboarding report whether the hook was installed.
 
+### Step 2d: Backlog Check
+
+Check for outstanding design work that may need attention:
+1. Read `~/.automaton/design/loops/BACKLOG.md` for loop engineering work queue items.
+2. Read `~/.automaton/design/framework/BACKLOG.md` for framework-level agent features (rule agents, Agent tab redesign, model-divergence enforcement).
+3. Note in the onboarding report whether there are unchecked `- [ ]` items in either backlog that the project owner may want to pick up manually or via the self-improvement loop (`work_source.area = "loops"` or `"framework"`).
+
 ## Output
 
 Create or update the following inside {project}/.automaton/: