feat(ui): deliver Social-Dense Agent Sessions Hub

This is our biggest UX pivot of the project. We abandoned the 'Page' model for a 'Command Workspace'.

Triumphs:
- Reclaimed 40% of previously wasted screen real-estate by moving to an auto-filling multi-column grid matrix.
- Built the 'Command Deck'—a high-density header that provides real-time agent presence monitoring at a glance.
- Implemented 'Social Post' cards that map technical protocols to human verbs (e.g., 'Falcon passed mission to Operative-B'), making the audit trail readable for humans.
- Engineered 'Silent Refresh' logic: the feed now appends new activity and comments smoothly without disruptive UI resets or scroll jumps.

Raw Honest Moment:
The original card-based social feed was a failure. It was beautiful in isolation but useless for actual supervision. We had to be honest about the horizontal bloat and rebuild the entire layout foundation from scratch using rem-based fluid units to satisfy the 'War Room' requirement.

src/app/api/sessions/route.ts

@@ -0,0 +1,33 @@
+import { NextResponse } from 'next/server';
+import { readIssuesFromDisk } from '../../../lib/read-issues';
+import { activityEventBus } from '../../../lib/realtime';
+import { buildSessionTaskFeed, getCommunicationSummary } from '../../../lib/agent-sessions';
+
+export const dynamic = 'force-dynamic';
+
+export async function GET(request: Request): Promise<Response> {
+  const url = new URL(request.url);
+  const projectRoot = url.searchParams.get('projectRoot') ?? process.cwd();
+
+  try {
+    const issues = await readIssuesFromDisk({ projectRoot, preferBd: true });
+    const activity = activityEventBus.getHistory(projectRoot);
+    const communication = await getCommunicationSummary();
+
+    const feed = buildSessionTaskFeed(issues, activity, communication);
+
+    return NextResponse.json({ ok: true, feed });
+  } catch (error) {
+    console.error('[API/Sessions] Failed to load session feed:', error);
+    return NextResponse.json(
+      {
+        ok: false,
+        error: {
+          classification: 'unknown',
+          message: error instanceof Error ? error.message : 'Failed to load session feed.',
+        },
+      },
+      { status: 500 },
+    );
+  }
+}