fix(P2): peer add rollback, helper failure recovery, manager extraction (A2/A3/A5)

A3 — Peer add atomicity: track firewall_applied flag and call
clear_peer_rules() during rollback so partial peer-add failures
don't leave stale iptables rules behind. Added test.

A2 — Pending config flag: instead of clearing before spawning the
helper container (fire-and-forget), set applying=True and let the
helper clear it on success by writing to cell_config.json via a
mounted /app/data volume. On API restart after a failed apply,
_recover_pending_apply() resets the applying flag so the UI shows
pending changes and the user can retry. GET /api/config/pending now
includes the applying field.

A5 (foundation) — Extract all manager instantiation into managers.py.
app.py re-exports every name so existing test patches (patch('app.X'))
continue to work unchanged. 1021 unit tests pass.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/test_peer_provisioning.py

@@ -370,3 +370,50 @@ def test_delete_nonexistent_peer_returns_gracefully(admin_client, mock_peer_regi
     r = _delete_peer(admin_client, 'nobody')
     # Route must not 500 when the peer simply doesn't exist
     assert r.status_code in (200, 404)
+
+
+# ── POST /api/peers — firewall rollback (A3) ──────────────────────────────────
+
+def test_create_peer_rolls_back_firewall_on_dns_failure(
+        auth_mgr, mock_email_mgr, mock_calendar_mgr,
+        mock_file_mgr, mock_wg_mgr, mock_peer_registry):
+    """If apply_all_dns_rules raises after firewall rules were applied, the peer
+    add must call clear_peer_rules to undo the firewall state (A3 fix)."""
+    app.config['TESTING'] = True
+    app.config['SECRET_KEY'] = 'test-secret'
+
+    mock_fw = MagicMock()
+    mock_fw.apply_peer_rules.return_value = True
+    mock_fw.apply_all_dns_rules.side_effect = RuntimeError('CoreDNS unreachable')
+
+    patches = [
+        patch('app.auth_manager', auth_mgr),
+        patch('app.email_manager', mock_email_mgr),
+        patch('app.calendar_manager', mock_calendar_mgr),
+        patch('app.file_manager', mock_file_mgr),
+        patch('app.wireguard_manager', mock_wg_mgr),
+        patch('app.peer_registry', mock_peer_registry),
+        patch('app.firewall_manager', mock_fw),
+    ]
+    try:
+        import auth_routes
+        patches.append(patch.object(auth_routes, 'auth_manager', auth_mgr, create=True))
+    except (ImportError, AttributeError):
+        pass
+
+    started = [p.start() for p in patches]
+    try:
+        with app.test_client() as client:
+            r = _login(client)
+            assert r.status_code == 200
+            resp = _post_peer(client)
+            assert resp.status_code == 500, (
+                f'expected 500 on DNS failure but got {resp.status_code}'
+            )
+            # Firewall rules must be cleared as part of rollback
+            mock_fw.clear_peer_rules.assert_called_once()
+            # Registry entry must also be rolled back
+            mock_peer_registry.remove_peer.assert_called_once()
+    finally:
+        for p in patches:
+            p.stop()