refactor: fake room routing moved to connect-time, fully decoupled from production

- server.py / main.py no longer reference fake_room at all (no import,
  no --fake-room flag, no _apply_fake_room)
- Routing decision happens at connect time in DanmakuClient.start():
  room_id == 1 dynamically imports fake_room.py and patches blivedm;
  any other room id returns immediately without touching fake_room
- Switching back from room 1 to another room unpatches to real Bilibili
- Production (packaged, no fake_room.py) is completely unaffected for
  normal room ids; room 1 without fake_room.py raises a clear error
- Rebuild portable zip (83.9 MB)

danmaku_handler.py

@@ -7,6 +7,7 @@ Rules come from event_rules.json (see event_rules.py).
 
 import asyncio
 import logging
+import sys
 from typing import Optional
 
 import blivedm
@@ -20,6 +21,27 @@ from event_rules import (
 
 logger = logging.getLogger(__name__)
 
+FAKE_ROOM_PORT = 8081  # fake_room.py default = bot web UI port (8080) + 1
+
+
+def _maybe_apply_fake_room(room_id: int) -> None:
+    """Connect-time routing: room_id == 1 uses the local fake_room.py (dev only).
+
+    fake_room.py is gitignored and never packaged. For any other room id this
+    returns immediately without ever importing fake_room, so production
+    (which has no fake_room.py) is completely unaffected.
+    """
+    fake = sys.modules.get("fake_room")
+    if room_id == 1:
+        if fake is None:
+            import importlib
+            fake = importlib.import_module("fake_room")
+        fake.patch_blivedm(FAKE_ROOM_PORT)
+        logger.info("[dev] room 1 -> fake room on port %d", FAKE_ROOM_PORT)
+    elif fake is not None:
+        # previously routed to fake room; switch back to real Bilibili
+        fake.unpatch_blivedm()
+
 INTERACT_TYPE_NAMES = {
     3: "\u5206\u4eab", 4: "\u7279\u522b\u5173\u6ce8", 5: "\u4e92\u7c89",
 }
@@ -178,6 +200,7 @@ class DanmakuClient:
 
     async def start(self) -> None:
         import aiohttp
+        _maybe_apply_fake_room(self._room_id)
         self._session = await build_danmaku_session(self._cookies)
         self._client = blivedm.BLiveClient(self._room_id, session=self._session)
         handler = DanmakuHandler(self._queue, self._rules)