merge: reconcile PR 40 with current lab

Integrate lab fff55a78 into PR #40 (cc25d5ba). Lab's modular email
backend/frontend, modular settings, split stylesheets (static/style.css
stays deleted), procfs compatibility, and request-scoped TurnContract
authority win; PR #40's routing classifiers, editor/email/task features,
and style.css changes are ported into lab's module and stylesheet homes.

Integration fixes:
- settings/api.js imports ui.js under its canonical versioned URL
- browser observations keep legacy CAPTCHA/access-block evidence
- artifact turns do not re-trigger broad-web research recovery
- env reference documents PR test-tool variables; page regenerated

PR #40 defects surfaced by lab gates and fixed here:
- web_fetch generic schema drops top-level anyOf (OpenAI contract);
  the compact preview contract still requires url or urls
- get_weather registered as a brokered network read
- new lazy editor modules precached for offline use
- SearXNG pin mirrored into GPU standalone compose files
- image model picker again skips offline endpoints

Tests updated where PR #40 changed behaviour on purpose, and PR tests
moved onto lab's document_source helpers.

tests/test_browser_transport_recovery.py

@@ -107,9 +107,9 @@ async def test_stream_recovers_navigation_then_fetch_without_email_classifier(mo
                   {'role': 'user', 'content': URL}],
         session_id='fixture-browser', owner='test', disabled_tools=set(), tool_policy=policy)]
     assert calls == ['private_browser', 'web_fetch', 'web_search'], '\n'.join(chunks)
-    assert requests[1]['tool_choice'] == 'required'
+    assert requests[1]['tool_choice'] == 'auto'
     assert [s['function']['name'] for s in requests[1]['tools']] == ['web_fetch']
-    assert requests[2]['tool_choice'] == 'required'
+    assert requests[2]['tool_choice'] == 'auto'
     assert [s['function']['name'] for s in requests[2]['tools']] == ['web_search']
     assert any('browser_transport_fallback' in chunk for chunk in chunks)
     assert any('[DONE]' in chunk for chunk in chunks)