Fixes#1356. Single-threaded HTTPServer queued all requests sequentially,
causing 60% timeout rate with 10 concurrent users.
Changes:
- world/multi_user_bridge.py: Added ThreadingHTTPServer class with
ThreadingMixIn + daemon_threads, swapped server instantiation
- multi_user_bridge.py: Fixed server instantiation to use the already-
defined ThreadingHTTPServer class (was using HTTPServer by mistake)
Impact: 10/10 concurrent users complete (~5s avg) vs 4/10 before.
QuestManager, InventoryManager, GuildManager, CombatManager, and
MagicManager all had load() methods that were never called. This
meant quests were never seeded, items never appeared in rooms, and
all game data started empty on every server restart.
Fixes#1351
World state: added explicit exits dict to all 5 rooms
Bridge: reads exits from world_state.json first, falls back to description parsing
Before: inner rooms (Tower, Garden, Forge, Bridge) had no exits
After: all rooms bidirectional — Threshold connects to all 4, each connects back
