feat: connectivity redesign phase 2 — instance-aware routing + reference connections by id

apply_routes now iterates over connection instances rather than types:
each instance gets its own fwmark, routing table, interface, and
redirect_port via _routing_connections / _resolve_peer_connection /
_apply_connection_for_src; kill-switch is enforced per iface-instance.
Old per-type MARKS/TABLES constants are kept only as migration scaffolding.

peer_registry: exit_via is now stored as a connection id (or 'default');
_migrate_exit_via_to_connection_id runs on _load_peers to upgrade legacy
type-string values; set_peer_exit_via validates against known connection
ids; VALID_EXIT_VIA removed; config_manager wired in from managers.py.

egress_manager: egress_overrides keyed by service_id → connection_id;
local MARKS/TABLES/EXIT_TYPES/_REDIRECT_PORTS/_add_tor_redirect removed;
(mark, table, redirect_port) resolved at apply-time via
connectivity_manager.get_connection; manifest egress.allowed still
enforced by connection type.

api/app.py + api.js: PUT peer/service exit endpoints accept {connection_id};
back-compat shim resolves a legacy type string to its single active instance.

Tests extended: two same-type instances produce distinct marks/tables/ports;
peer exit_via and egress override id migrations round-trip correctly;
single-instance behaviour is equivalent to the old type-keyed path.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

api/managers.py

@@ -53,7 +53,8 @@ service_registry = ServiceRegistry(config_manager=config_manager)
 network_manager    = NetworkManager(data_dir=DATA_DIR, config_dir=CONFIG_DIR,
                                     service_registry=service_registry)
 wireguard_manager  = WireGuardManager(data_dir=DATA_DIR, config_dir=CONFIG_DIR)
-peer_registry      = PeerRegistry(data_dir=DATA_DIR, config_dir=CONFIG_DIR)
+peer_registry      = PeerRegistry(data_dir=DATA_DIR, config_dir=CONFIG_DIR,
+                                  config_manager=config_manager)
 email_manager      = EmailManager(data_dir=DATA_DIR, config_dir=CONFIG_DIR, service_bus=service_bus)
 calendar_manager   = CalendarManager(data_dir=DATA_DIR, config_dir=CONFIG_DIR)
 file_manager       = FileManager(data_dir=DATA_DIR, config_dir=CONFIG_DIR)
@@ -102,6 +103,7 @@ from egress_manager import EgressManager
 egress_manager = EgressManager(
     config_manager=config_manager,
     service_store_manager=service_store_manager,
+    connectivity_manager=connectivity_manager,
     data_dir=DATA_DIR,
     config_dir=CONFIG_DIR,
 )