fix: run full reload after HTTP config publish, not just config.reload()

HTTP config-mutating endpoints (publish, rollback, channel CRUD, user
self-update) were calling config.reload() directly, which only refreshed
the in-memory config dict. This skipped re-applying host.dyn/host.watched
flags to live Host objects, so enabling dyndns via the UI had no effect
until a SIGHUP was sent.

Wire a reload_callback through http.start() that calls the same
reload_configuration() function used by the SIGHUP handler, ensuring
host attributes, notify module, users, and threshold checker are all
updated on every config publish.

Also fix unmatched quote in udp.py f-string log message.

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

hbd/server/udp.py

@@ -377,7 +377,7 @@ def handle_datagram(msg: dict, addr, transport, ctx: dict):
                 default_owner = config_mod.get_default_owner(cfg)
                 inferred_owner = plugin_data.get("owner", config_owner or default_owner)    
                 host.owner = inferred_owner
-                logger.info(f"owner for {uname} is '{host.owner}")
+                logger.info(f"owner for {uname} is {host.owner}")
             if DEBUG > 1:
                 print(f"Stored plugin data for {uname}: {plugin_name}")