feat(frontend): update sessions page for enhanced health monitoring

- Add new status badges: starting, probing, unhealthy
- Show tunnel error only when tunnel_status is unreachable
- Show app error badge with status code for error_response
- Add collapsible probe output section for diagnostics
- Update health polling to check all active instances
- Only show Recreate Tunnel button for unreachable tunnels

apps/web/src/api/sessions.ts

@@ -25,6 +25,8 @@ export interface Session {
   project_id: string;
   status: string;
   url: string | null;
+  container_status?: string;
+  probe_status?: string;
 }
 
 export async function listInstances(
@@ -101,11 +103,23 @@ export async function getUserSessions(): Promise<Session[]> {
   return response.data.sessions;
 }
 
+export interface InstanceHealth {
+  healthy: boolean;
+  container_status: string;
+  container_health?: string;
+  container_exit_code?: number | null;
+  tunnel_status: string;
+  tunnel_status_code: number | null;
+  probe_status: string;
+  last_probe_output?: string;
+  error?: string;
+}
+
 export async function checkInstanceHealth(
   projectId: string,
   repoId: string,
   instanceId: string
-): Promise<{ healthy: boolean; status_code: number | null; error?: string }> {
+): Promise<InstanceHealth> {
   const response = await apiClient.get(
     `/projects/${projectId}/repositories/${repoId}/instances/${instanceId}/health`
   );