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_pr6020_browser_review_regressions.py

@@ -502,10 +502,13 @@ def test_superseded_stream_cleanup_leaves_replacement_state_alone():
       function _setForegroundChatBusy() {{}}
       const window = {{}};
       const sessionModule = {{ getCurrentSessionId() {{ return 'session-1'; }} }};
+      let docFinalized = 0;
+      const documentModule = {{ streamDocFinalize() {{ docFinalized += 1; }} }};
       {state_and_stop}
       function runCleanup(abortCtrl, streamGeneration) {{
         const streamSessionId = 'session-1';
         const _sendState = {{ generation: streamGeneration, abortCtrl }};
+        const _streamSawDone = false;
         {finally_cleanup}
         return _ownsStreamState;
       }}
@@ -520,6 +523,7 @@ def test_superseded_stream_cleanup_leaves_replacement_state_alone():
       _pendingRunStops.set('session-1:2', newCtrl);
       const preRegOwns = runCleanup(oldCtrl, 1);
       const afterPreReg = {{
+        docFinalized,
         ownEntryRemoved: !_activeStreams.has('session-1'),
         replacementPendingKept: _pendingRunStops.has('session-1:2'),
         sessionKept: _streamSessionId === 'session-1',
@@ -528,6 +532,7 @@ def test_superseded_stream_cleanup_leaves_replacement_state_alone():
       _activeStreams.set('session-1', {{ abortCtrl: newCtrl, holder: null, lastActivity: 2 }});
       const postRegOwns = runCleanup(oldCtrl, 1);
       const afterPostReg = {{
+        docFinalized,
         replacementRegistrationKept: _activeStreams.has('session-1'),
         replacementPendingKept: _pendingRunStops.has('session-1:2'),
         sessionKept: _streamSessionId === 'session-1',
@@ -535,6 +540,7 @@ def test_superseded_stream_cleanup_leaves_replacement_state_alone():
       // Owner: the current-generation send cleans up normally.
       const ownerOwns = runCleanup(newCtrl, 2);
       const afterOwner = {{
+        docFinalized,
         registered: _activeStreams.has('session-1'),
         pendingKept: _pendingRunStops.has('session-1:2'),
         sessionCleared: _streamSessionId === null,
@@ -547,18 +553,22 @@ def test_superseded_stream_cleanup_leaves_replacement_state_alone():
     assert _run_node(script) == {
         "preRegOwns": False,
         "afterPreReg": {
+            # A superseded send must not finalize the replacement's document stream.
+            "docFinalized": 0,
             "ownEntryRemoved": True,
             "replacementPendingKept": True,
             "sessionKept": True,
         },
         "postRegOwns": False,
         "afterPostReg": {
+            "docFinalized": 0,
             "replacementRegistrationKept": True,
             "replacementPendingKept": True,
             "sessionKept": True,
         },
         "ownerOwns": True,
         "afterOwner": {
+            "docFinalized": 1,
             "registered": False,
             "pendingKept": False,
             "sessionCleared": True,