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).

README.md

@@ -250,6 +250,7 @@ The runner resolves prompt files from `loop.json` `roles.*.prompt` (e.g. `loop-i
 | `blast_radius.file_scope` | List of paths the loop may edit |
 | `blast_radius.use_worktree` | If true, tick runs in a per-loop git worktree |
 | `work_source.kind` | `single`, `audit`, or `backlog` |
+| `work_source.area` | Design area for `backlog` kind (default `"loops"`; `"framework"` reads `design/framework/BACKLOG.md`) |
 | `roles.implement.prompt` | Prompt file for Implement role |
 | `roles.verify.prompt` | Prompt file for Verify role |
 | `roles.orchestrate.prompt` | Prompt file for Orchestrate role |