fix(HEL-487): 盘中当天看板在 rt_k 无权限时降级到免费实时源

rt_k 失败、无权限、超时或空结果时改用东财全市场快照，再失败则用腾讯批量行情；两者都失败仍不退回昨天。

Co-authored-by: Cursor <cursoragent@cursor.com>
Co-authored-by: multica-agent <github@multica.ai>

config/architecture-inventory.json

@@ -222,12 +222,12 @@
     {
       "provider": "eastmoney",
       "path": "backend/data/realtime.py",
-      "runtime_role": "isolated realtime observation"
+      "runtime_role": "isolated realtime observation and intraday dashboard fallback"
     },
     {
       "provider": "tencent",
       "path": "backend/data/realtime.py",
-      "runtime_role": "index observation fallback"
+      "runtime_role": "index observation and intraday quote fallback"
     }
   ],
   "provider_domains": [
@@ -508,8 +508,8 @@
     },
     {
       "path": "backend/data/providers/tushare_dashboard.py",
-      "bytes": 28327,
-      "lines": 654
+      "bytes": 31361,
+      "lines": 732
     },
     {
       "path": "backend/data/providers/tushare_industries.py",
@@ -631,6 +631,11 @@
       "bytes": 8357,
       "lines": 116
     },
+    {
+      "path": "backend/data/providers/tushare_indices.py",
+      "bytes": 7823,
+      "lines": 173
+    },
     {
       "path": "backend/features/screener/formula.py",
       "bytes": 6983,
@@ -686,11 +691,6 @@
       "bytes": 5690,
       "lines": 124
     },
-    {
-      "path": "backend/data/providers/tushare_indices.py",
-      "bytes": 5451,
-      "lines": 118
-    },
     {
       "path": "frontend/pages.config.js",
       "bytes": 5385,