Fix module subprocess lifecycle and capture_bus injection bugs

Three bugs causing all modules to exit within seconds of startup:

1. _module_runner had no keep-alive loop after calling module.start().
   All modules use a thread-spawning pattern where start() returns
   immediately, so the subprocess exited and killed all daemon threads.
   Added while module._running: sleep(1) loop to block until stop().

2. Engine injected capture_bus under key 'capture_bus' but 9 modules
   (auth_flow_tracker, cloud_token_harvester, ldap_harvester, network_mapper,
   rdp_monitor, quic_analyzer, smb_monitor, db_interceptor, vlan_discovery)
   look for '_capture_bus'. Inject both keys so all modules get it.

3. mac_manager crashes on startup when innocuous_macs.db exists but has
   no mac_profiles table (DB not yet seeded). Added OperationalError
   handler to fall back to random OUI instead of crashing.

modules/stealth/mac_manager.py

@@ -210,6 +210,9 @@ class MacManager(BaseModule):
             if rows:
                 return dict(random.choice(rows))
             return None
+        except sqlite3.OperationalError:
+            logger.warning("mac_profiles table missing — DB not seeded, using fallback")
+            return None
         finally:
             conn.close()