fix: orchestrator button + Pi SDK session error

- Move leftSidebarMode from URL state to local useState in unified-shell,
    avoiding force-dynamic router round-trip that made the button appear broken                                           - Replace fileURLToPath(new URL(..., import.meta.url)) with process.cwd()
    in bb-pi-bootstrap.ts — import.meta.url is a webpack:// URL in Next.js,
    causing cross-realm TypeError when passed to Node.js fileURLToPath()

src/app/api/runtime/launch/route.ts

@@ -0,0 +1,55 @@
+import { NextResponse } from 'next/server';
+import { bbDaemon } from '../../../../lib/bb-daemon';
+import type { LaunchSurface } from '../../../../lib/embedded-runtime';
+import type { readIssuesFromDisk as ReadIssuesFromDisk } from '../../../../lib/read-issues';
+
+export const dynamic = 'force-dynamic';
+
+interface LaunchDeps {
+  readIssues?: typeof ReadIssuesFromDisk;
+}
+
+function isLaunchSurface(value: string): value is LaunchSurface {
+  return ['social', 'graph', 'swarm', 'sessions', 'activity', 'task'].includes(value);
+}
+
+export async function handleRuntimeLaunchPost(request: Request, deps: LaunchDeps = {}): Promise<Response> {
+  try {
+    const body = await request.json();
+    const projectRoot = typeof body?.projectRoot === 'string' ? body.projectRoot.trim() : '';
+    const taskId = typeof body?.taskId === 'string' ? body.taskId.trim() : '';
+    const origin = typeof body?.origin === 'string' && isLaunchSurface(body.origin) ? body.origin : null;
+    const swarmId = typeof body?.swarmId === 'string' ? body.swarmId : null;
+
+    if (!projectRoot || !taskId || !origin) {
+      return NextResponse.json({ ok: false, error: 'projectRoot, taskId, and origin are required' }, { status: 400 });
+    }
+
+    const read = deps.readIssues ?? (await import('../../../../lib/read-issues')).readIssuesFromDisk;
+    const issues = await read({ projectRoot, preferBd: true });
+    const issue = issues.find((entry) => entry.id === taskId);
+
+    if (!issue) {
+      return NextResponse.json({ ok: false, error: 'task not found' }, { status: 404 });
+    }
+
+    const lifecycle = await bbDaemon.ensureRunning();
+    const result = await bbDaemon.launchFromIssue({
+      projectRoot,
+      issue,
+      origin,
+      swarmId,
+    });
+
+    return NextResponse.json({ ok: true, lifecycle, data: result });
+  } catch (error) {
+    return NextResponse.json(
+      { ok: false, error: error instanceof Error ? error.message : 'Invalid request' },
+      { status: 400 },
+    );
+  }
+}
+
+export async function POST(request: Request): Promise<Response> {
+  return handleRuntimeLaunchPost(request);
+}