Restore archived tasks, fix dashboard scroll-reset, bind ornith, add Playwright smoke test

- **Restore 82 completed tasks** from tasks/complete/ back to tasks/ top
  level (all <7 days old per the cleanup policy; premature bulk archive
  was fixed).
- **Dashboard: fix scroll-reset on auto-refresh** — renderBoard rebuilds
  the board via innerHTML every 2s, destroying each column-body's
  scrollTop. Now snapshots column-body scrollTop + board.scrollLeft +
  view.scrollTop before rebuild and restores after (matched by
  PHASE_GROUPS index).
- **Dashboard UI additions** (pre-existing unstaged work): approval
  section cards, transition buttons, inline artifact editor (textarea for
  writing missing SPEC/VERDICT/etc from the detail modal).
- **Bind ornith as Implement model** — config.md: Model explicit to
  omlx/Ornith-1.0-35B-4bit-mlx, context window 32768. Interactive
  autopilot already used ornith via opencode default; now explicit.
- **Fix cleanup stub** — automaton-cleanup.sh had a stale --project arg
  pointing at a pytest temp dir (test isolation leak). Rewired to point
  at ~/.automaton.
- **Fix plist-isolation test** — test asserted host plist doesn't exist,
  but a real install creates it. Now snapshots mtime before run, asserts
  unchanged after (only a write during the test counts as bleed).
- **New Playwright smoke test** (tests/test_dashboard_ui.py) — 2 tests:
  board renders tasks, column scroll survives auto-refresh tick.
  Verified the test fails without the scroll fix (scrollTop resets to 0).
  Skipped via importorskip when playwright is absent (main CI stays
  green).
- **Clarify SI loop scope in README** — new-project onboarding section
  documents the framework-scoped self-improvement loop and options
  (leave/pause/create project loop).
- **CHANGELOG** documents all changes including the known model-divergence
  gap (mde tasks marked complete but per-role model binding was never
  implemented).

tasks/additive-extension-model/IMPLEMENTATION.md

@@ -0,0 +1,34 @@
+# Implementation: Additive Extension Model
+
+## Summary
+
+Replaced the diff/merge upgrade process with an additive extension model. Projects no longer copy framework files — they provide overrides via `.agent.md`, `.rules.md`, and an optional `extensions/` directory.
+
+## Changes Made
+
+### `prompts/orchestrate.md`
+- Base framework files (prompts, contracts, scripts) now always read from `~/.automaton/`
+- Projects provide additive extensions under `{project}/.automaton/extensions/`
+- Extension read order: project extensions loaded after (or before for scripts) corresponding global files
+- `.agent.md` and `.rules.md` remain layered (project override first)
+
+### `prompts/onboarding.md`
+- Removed the diff/merge "Project Upgrade" section
+- Simplified to create minimal `.agent.md` and `.rules.md` if missing
+- Documents the `extensions/` directory pattern
+- Explicitly states projects should never copy framework files
+
+### `scripts/update.sh`
+- Simplified to plain `git pull origin main`
+- Removed `reset hard HEAD` step — never touches project directories
+
+### `README.md`
+- Updated "Upgrading existing projects" section for the additive model
+- Documents the `extensions/` directory pattern
+- Migration path for old-model projects
+
+## Files Modified
+- `prompts/orchestrate.md` — reordered read precedence, added extension checks
+- `prompts/onboarding.md` — removed diff/merge section, simplified setup
+- `scripts/update.sh` — simplified to plain git pull
+- `README.md` — documented new upgrade model