chore: remove Max Participants debug instrumentation (verified working)

Reverts the temporary fetch()-based debug instrumentation added in
a808caa (the "Debug instrumentation" section of that commit's message):

* frontend/src/App.js (handleMaxParticipantsChange):
- Removed the `// #region agent log` POST to 127.0.0.1:7660 that
forwarded n / clamped / prev maxParticipants state to the local
debug server.
- Reverted the useCallback deps from [selectedIds, maxParticipants]
back to [selectedIds]; `maxParticipants` was only in the deps
because the instrumentation closed over it.

* frontend/src/components/DevMenu.js:
- Removed the panel-open render-snapshot useEffect that POSTed to
127.0.0.1:7660.
- Restored the +/- stepper button onClick handlers to their original
one-liner form (Math.max(3, ...) / Math.min(9, ...)), removing the
wrapped click handlers that POSTed click-snapshots to the debug
server.

All non-instrumentation changes from a808caa (DownloadMenu split,
Header prop wiring fix for maxParticipants, settings-menu restructure,
theme toggle, contrast tweaks, etc.) are preserved.

No production code paths reference 127.0.0.1:7660,
b27d4bb5-c1ab-4767-aa98-1cdf1e8fb0ae, X-Debug-Session-Id, or session
id 896623 anymore. The debug-896623.log file was not present in the
working tree or git index, so no file deletion was needed.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/App.js

@@ -191,34 +191,11 @@ export default function App() {
   }, []);
   const handleMaxParticipantsChange = useCallback((n) => {
     const clamped = Math.max(3, Math.min(9, n));
-    // #region agent log
-    fetch('http://127.0.0.1:7660/ingest/b27d4bb5-c1ab-4767-aa98-1cdf1e8fb0ae', {
-      method: 'POST',
-      headers: { 'Content-Type': 'application/json', 'X-Debug-Session-Id': '896623' },
-      body: JSON.stringify({
-        sessionId: '896623',
-        runId: 'maxparticipants-repro',
-        hypothesisId: 'H2',
-        location: 'App.js:handleMaxParticipantsChange',
-        message: 'Parent handler invoked',
-        data: {
-          n,
-          nType: typeof n,
-          nIsNaN: Number.isNaN(n),
-          clamped,
-          clampedIsNaN: Number.isNaN(clamped),
-          prevMaxParticipants: maxParticipants,
-          prevMaxParticipantsType: typeof maxParticipants,
-        },
-        timestamp: Date.now(),
-      }),
-    }).catch(() => {});
-    // #endregion
     setMaxParticipants(clamped);
     if (selectedIds.length > clamped) {
       setSelectedIds(prev => prev.slice(0, clamped));
     }
-  }, [selectedIds, maxParticipants]);
+  }, [selectedIds]);
   const handleModelAssignmentChange = useCallback((participantId, modelId) => {
     setModelAssignments(prev => {
       const next = { ...prev };

frontend/src/components/DevMenu.js

@@ -90,31 +90,6 @@ export default function DevMenu({
     });
   }, [allModels, q]);
 
-  // #region agent log
-  useEffect(() => {
-    if (!open) return;
-    fetch('http://127.0.0.1:7660/ingest/b27d4bb5-c1ab-4767-aa98-1cdf1e8fb0ae', {
-      method: 'POST',
-      headers: { 'Content-Type': 'application/json', 'X-Debug-Session-Id': '896623' },
-      body: JSON.stringify({
-        sessionId: '896623',
-        runId: 'maxparticipants-repro',
-        hypothesisId: 'H1',
-        location: 'DevMenu.js:render',
-        message: 'DevMenu render snapshot (panel open)',
-        data: {
-          maxParticipants,
-          maxParticipantsType: typeof maxParticipants,
-          onMaxParticipantsChangeType: typeof onMaxParticipantsChange,
-          ge9: maxParticipants >= 9,
-          le3: maxParticipants <= 3,
-        },
-        timestamp: Date.now(),
-      }),
-    }).catch(() => {});
-  }, [open, maxParticipants, onMaxParticipantsChange]);
-  // #endregion
-
   const nameForModel = (id) => {
     if (!id) return null;
     const m = allModels.find(x => x.id === id);
@@ -190,63 +165,13 @@ export default function DevMenu({
               <button
                 className="btn-sm btn-outline ccai-stepper-btn"
                 disabled={maxParticipants <= 3}
-                onClick={() => {
-                  const next = Math.max(3, maxParticipants - 1);
-                  // #region agent log
-                  fetch('http://127.0.0.1:7660/ingest/b27d4bb5-c1ab-4767-aa98-1cdf1e8fb0ae', {
-                    method: 'POST',
-                    headers: { 'Content-Type': 'application/json', 'X-Debug-Session-Id': '896623' },
-                    body: JSON.stringify({
-                      sessionId: '896623',
-                      runId: 'maxparticipants-repro',
-                      hypothesisId: 'H1',
-                      location: 'DevMenu.js:onMinusClick',
-                      message: 'Minus button clicked',
-                      data: {
-                        maxParticipants,
-                        maxParticipantsType: typeof maxParticipants,
-                        next,
-                        nextType: typeof next,
-                        nextIsNaN: Number.isNaN(next),
-                        onMaxParticipantsChangeType: typeof onMaxParticipantsChange,
-                      },
-                      timestamp: Date.now(),
-                    }),
-                  }).catch(() => {});
-                  // #endregion
-                  onMaxParticipantsChange(next);
-                }}
+                onClick={() => onMaxParticipantsChange(Math.max(3, maxParticipants - 1))}
               >−</button>
               <div className="ccai-stepper-val">{maxParticipants}</div>
               <button
                 className="btn-sm btn-outline ccai-stepper-btn"
                 disabled={maxParticipants >= 9}
-                onClick={() => {
-                  const next = Math.min(9, maxParticipants + 1);
-                  // #region agent log
-                  fetch('http://127.0.0.1:7660/ingest/b27d4bb5-c1ab-4767-aa98-1cdf1e8fb0ae', {
-                    method: 'POST',
-                    headers: { 'Content-Type': 'application/json', 'X-Debug-Session-Id': '896623' },
-                    body: JSON.stringify({
-                      sessionId: '896623',
-                      runId: 'maxparticipants-repro',
-                      hypothesisId: 'H1',
-                      location: 'DevMenu.js:onPlusClick',
-                      message: 'Plus button clicked',
-                      data: {
-                        maxParticipants,
-                        maxParticipantsType: typeof maxParticipants,
-                        next,
-                        nextType: typeof next,
-                        nextIsNaN: Number.isNaN(next),
-                        onMaxParticipantsChangeType: typeof onMaxParticipantsChange,
-                      },
-                      timestamp: Date.now(),
-                    }),
-                  }).catch(() => {});
-                  // #endregion
-                  onMaxParticipantsChange(next);
-                }}
+                onClick={() => onMaxParticipantsChange(Math.min(9, maxParticipants + 1))}
               >+</button>
               <span className="dev-panel-hint">3-9</span>
             </div>