fix: WeChat session context via X-Hermes-Session-Id (revert SessionRouter)

SessionRouter approach failed on Linux because chat_bridge.py has
hardcoded Windows paths for provider config and opencode.db.

Instead, use the same pattern as xmpp_agent_core.py: direct Hermes API
call with X-Hermes-Session-Id=wechat-{sender_id} for per-user sessions.

This gives each WeChat user persistent context in Hermes without
depending on cross-platform path issues in chat_bridge.py.

gateway/linux/wechat_webhook.py

@@ -1,16 +1,9 @@
 #!/usr/bin/env python3
-"""WeChat webhook receiver v2 - receives messages from docker-wechatbot-webhook."""
+"""WeChat webhook receiver v3 — per-user session context via Hermes session ID."""
 
 import os, sys, json, logging, threading, queue, time
 from http.server import HTTPServer, BaseHTTPRequestHandler
 
-# ── MoFin session routing (shared with XMPP) ──
-_SCRIPTS_DIR = os.path.join(os.path.dirname(os.path.dirname(os.path.abspath(__file__))), "scripts")
-if _SCRIPTS_DIR not in sys.path:
-    sys.path.insert(0, _SCRIPTS_DIR)
-from chat_bridge import SessionBridge
-from session_router import SessionRouter
-
 HERMES_API = "http://192.168.1.246:8646/v1/chat/completions"
 HERMES_KEY = "hermes123"
 PORT = 5804
@@ -30,12 +23,6 @@ logging.basicConfig(
 )
 log = logging.getLogger("wc-webhook")
 
-# ── Session router (per-user session context via opencode.db) ──
-_router = SessionRouter(
-    bridge=SessionBridge(session_id="wechat-mohe"),
-    default_session="wechat-mohe",
-)
-
 # ── 消息队列（串行处理，防止并发打爆 Hermes）──────────────
 _msg_queue = queue.Queue()
 
@@ -55,15 +42,34 @@ def _hermes_worker():
 
 
 def _do_forward(sender, sender_id, text):
-    """通过 SessionRouter 发送消息（自动带上下文 + 会话管理）。"""
+    """调用 Hermes API 并回复微信（带 X-Hermes-Session-Id 实现 per-user 上下文）。"""
+    session_id = f"wechat-{sender_id}"
+    payload = json.dumps({
+        "model": "nova-4",
+        "messages": [
+            {"role": "user", "content": f"[微信消息] 来自 {sender}({sender_id}): {text}"}
+        ]
+    }).encode()
+
     try:
-        reply = _router.route("wechat", sender_id, text)
-        log.info(f"Router OK, reply: {reply[:60] if reply else '(empty)'}")
+        import urllib.request as ureq
+        handler = ureq.ProxyHandler({})
+        opener = ureq.build_opener(handler)
+        req = ureq.Request(HERMES_API, data=payload,
+            headers={
+                "Content-Type": "application/json",
+                "Authorization": f"Bearer {HERMES_KEY}",
+                "X-Hermes-Session-Id": session_id,
+            })
+        resp = opener.open(req, timeout=600)
+        resp_data = json.loads(resp.read())
+        reply = resp_data.get('choices', [{}])[0].get('message', {}).get('content', '')
+        log.info(f"Hermes OK [{sender[:8]}], reply: {reply[:60]}")
 
         if reply and sender:
             WebhookHandler._send_wechat_static(sender, reply)
     except Exception as e:
-        log.error(f"Router error: {e}")
+        log.error(f"Hermes error [{sender[:8]}]: {e}")
 
 
 # 启动 worker 线程