fix: repair broken tests across alert, chanmgmt, and integration

- test_alert: remove stale _MAX_ANNOUNCE import/test, update _errors
  assertions for per-backend dict, fix announcement checks (action vs
  send), mock _fetch_og_batch in seeding tests, fix YouTube/SearX mock
  targets (urllib.request.urlopen), include keyword in fake data titles
- test_chanmgmt: add _FakeState to _FakeBot (on_invite now persists)
- test_integration: update help assertion for new output format

696 tests pass, 0 failures.

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

tests/test_chanmgmt.py

@@ -31,6 +31,26 @@ class _FakeConn:
         self.sent.append(raw)
 
 
+class _FakeState:
+    """In-memory stand-in for bot.state."""
+
+    def __init__(self):
+        self._store: dict[str, dict[str, str]] = {}
+
+    def get(self, plugin: str, key: str, default: str | None = None) -> str | None:
+        return self._store.get(plugin, {}).get(key, default)
+
+    def set(self, plugin: str, key: str, value: str) -> None:
+        self._store.setdefault(plugin, {})[key] = value
+
+    def delete(self, plugin: str, key: str) -> bool:
+        try:
+            del self._store[plugin][key]
+            return True
+        except KeyError:
+            return False
+
+
 class _FakeBot:
     """Minimal bot stand-in."""
 
@@ -38,6 +58,7 @@ class _FakeBot:
         self.joined: list[str] = []
         self._admin = admin
         self.conn = _FakeConn()
+        self.state = _FakeState()
 
     def _is_admin(self, message) -> bool:
         return self._admin