feat(frontend): team + engineer dropdowns on join screen

Replace free-text name/pod inputs with select-only dropdowns (pick a team,
then yourself from its members) for fast R&D iteration. Demo teams live in
lib/teams.ts until pods are persisted.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/lib/teams.ts

@@ -0,0 +1,31 @@
+/**
+ * Hardcoded teams/engineers for R&D so the join screen is select-only (no typing)
+ * while we develop. Swap for real data (backend/Atlas) once pods are persisted.
+ */
+export interface DemoTeam {
+  id: string;
+  name: string;
+  repo: string;
+  members: string[];
+}
+
+export const TEAMS: DemoTeam[] = [
+  {
+    id: 'demo-pod',
+    name: 'Demo Pod',
+    repo: 'karti-ai/podman',
+    members: ['Karti', 'Yahya', 'Ramis', 'Zander', 'Shakthi'],
+  },
+  {
+    id: 'frontend-squad',
+    name: 'Frontend Squad',
+    repo: 'karti-ai/podman',
+    members: ['Karti', 'Zander'],
+  },
+  {
+    id: 'backend-squad',
+    name: 'Backend Squad',
+    repo: 'karti-ai/podman',
+    members: ['Yahya', 'Ramis'],
+  },
+];