docs(diagrams): 架构图补 OpenCode Zen 渠道与按渠道凭证加载

- 新增 OpenCode Zen Provider（免费层 · 虚拟凭证）与 OpenCode Zen 上游节点
- 请求面视图补入 zen / zen-up；区域边界纳入 zen
- engine→zen 与 zen→zen-up（SSE）连接；zen 无后台任务故不加 bg 边
- 卡片同步：/v1/models 按渠道凭证加载；三渠道同池调度
- 用 archify 3.0.1 重新生成 HTML 与 visual-check 证据

Author: RobbsLuo

diagrams/architecture.json

@@ -20,8 +20,10 @@
           "engine",
           "cb",
           "trae",
+          "zen",
           "cb-up",
-          "trae-up"
+          "trae-up",
+          "zen-up"
         ],
         "note": "客户端请求经协议层规范化，由执行引擎选号后流式转发到上游。"
       },
@@ -206,6 +208,21 @@
         64
       ]
     },
+    {
+      "id": "zen",
+      "type": "backend",
+      "label": "OpenCode Zen Provider",
+      "sublabel": "免费层 · 虚拟凭证",
+      "pos": [
+        760,
+        540
+      ],
+      "size": [
+        140,
+        64
+      ],
+      "tag": "免费层"
+    },
     {
       "id": "cb-up",
       "type": "external",
@@ -234,6 +251,20 @@
         64
       ]
     },
+    {
+      "id": "zen-up",
+      "type": "external",
+      "label": "OpenCode Zen 上游",
+      "sublabel": "opencode.ai/zen",
+      "pos": [
+        980,
+        540
+      ],
+      "size": [
+        140,
+        64
+      ]
+    },
     {
       "id": "db",
       "type": "database",
@@ -260,6 +291,7 @@
         "cb",
         "bg",
         "trae",
+        "zen",
         "admin-ui",
         "admin-api",
         "identity",
@@ -317,6 +349,23 @@
         ]
       ]
     },
+    {
+      "id": "engine-to-zen",
+      "from": "engine",
+      "to": "zen",
+      "fromSide": "right",
+      "toSide": "left",
+      "via": [
+        [
+          720,
+          312
+        ],
+        [
+          720,
+          572
+        ]
+      ]
+    },
     {
       "id": "cb-to-cbup",
       "from": "cb",
@@ -331,6 +380,13 @@
       "label": "SSE",
       "variant": "emphasis"
     },
+    {
+      "id": "zen-to-zenup",
+      "from": "zen",
+      "to": "zen-up",
+      "label": "SSE",
+      "variant": "emphasis"
+    },
     {
       "id": "bg-to-cb",
       "from": "bg",
@@ -432,8 +488,8 @@
       "title": "对外契约",
       "items": [
         "/v1/chat/completions、/v1/responses",
-        "/v1/models + 黑名单；/v1/user/balance",
-        "/healthz 池健康、model@provider 选上游"
+        "/v1/models 按渠道凭证加载 + 黑名单",
+        "/v1/user/balance、/healthz 池健康"
       ]
     },
     {
@@ -442,7 +498,7 @@
       "items": [
         "选号：pin → 粘性 → 到期积分 → 三态健康度",
         "模型级冷却隔离到单个模型，不牵连整条凭证",
-        "6 个后台任务汇总进「任务与配置」页"
+        "三渠道同池调度；6 个后台任务汇总「任务与配置」"
       ]
     },
     {