fix: 修复3个问题

1. 对比度: --text-muted 从 #94a3b8 改为 #c8d6e5 (文字更亮)
2. 登录: auth.py 从 .env 文件读取密码，解决后台进程环境变量丢失
3. 实例创建: 同步 instances.py 的 db import (之前缺 import db)

.env

@@ -0,0 +1 @@
+SM_ADMIN_PASSWORD=test123

auth.py

@@ -7,10 +7,23 @@ bp = Blueprint("auth", __name__)
 
 
 def _get_admin_creds():
-    return (
-        os.environ.get("SM_ADMIN_USER", "admin"),
-        os.environ.get("SM_ADMIN_PASSWORD", ""),
-    )
+    import os
+    _ENV = "/root/socks-manager/.env"
+    pwd = os.environ.get("SM_ADMIN_PASSWORD")
+    user = os.environ.get("SM_ADMIN_USER", "admin")
+    if not pwd and os.path.exists(_ENV):
+        try:
+            for line in open(_ENV):
+                line = line.strip()
+                if line and not line.startswith("#"):
+                    k, _, v = line.partition("=")
+                    if k.strip() == "SM_ADMIN_PASSWORD":
+                        pwd = v.strip()
+                    elif k.strip() == "SM_ADMIN_USER":
+                        user = v.strip()
+        except Exception:
+            pass
+    return (user, pwd or "")
 
 
 def login_required(f):

engine/instances.py

@@ -141,6 +141,8 @@ class InstanceManager:
 
     def sync_instances(self):
         """根据数据库配置同步实例运行状态。"""
+        from models import Instance
+        from database import db
         self.reload_config()
 
         current_names = set(self._config_cache.keys())

templates/base.html

@@ -11,7 +11,7 @@
 /* ── 全局 ─────────────────────────────────────────────────────── */
 :root {
   --bg-primary:#0b0e14; --bg-secondary:#161922; --bg-tertiary:#1e2235;
-  --border:#1f2335; --text:#e2e8f0; --text-muted:#94a3b8;
+  --border:#1f2335; --text:#e2e8f0; --text-muted:#c8d6e5;
   --accent:#818cf8; --accent-hover:#6366f1;
   --green:#10b981; --red:#ef4444; --yellow:#f59e0b; --gray:#6b7280;
   --card-bg:#161922; --input-bg:#0b0e14;
@@ -19,7 +19,7 @@
 * { box-sizing:border-box; }
 body { background:var(--bg-primary); color:var(--text);
   font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"Helvetica Neue",Arial,sans-serif;
-  font-size:14px; line-height:1.6; }
+  font-size:16px; line-height:1.7; }
 a { color:var(--accent); text-decoration:none; }
 a:hover { color:var(--accent-hover); }