fix: cross-platform config path in chat_bridge.py

_load_providers and _SERVE_DB had hardcoded C:\\\\Users\\\\hmo paths.
Now uses os.path.expanduser(" ~\) as primary path, with Windows
fallback. Supports OPENCODE_CONFIG_PATH env override.

gateway/scripts/chat_bridge.py

@@ -340,7 +340,10 @@ def _search_all_sessions(query: str, max_sessions: int = 5) -> str:
         return f"(搜索出错: {e})"
 
 
-# ── Serve session DB path ──
+# ── Serve session DB path (cross-platform) ──
+_SERVE_DB = os.path.join(
+    os.path.expanduser("~"), ".local", "share", "opencode", "opencode.db")
+if sys.platform == "win32" and not os.path.exists(_SERVE_DB):
     _SERVE_DB = os.path.join(
         os.environ.get("USERPROFILE", "C:\\Users\\hmo"),
         ".local", "share", "opencode", "opencode.db")