refactor: establish frontend page modules

docs/governance/architecture-inventory.json

@@ -255,8 +255,8 @@
   "code_hotspots": [
     {
       "path": "static/app.js",
-      "bytes": 441609,
-      "lines": 9262
+      "bytes": 441313,
+      "lines": 9283
     },
     {
       "path": "static/styles.css",
@@ -275,8 +275,8 @@
     },
     {
       "path": "static/index.html",
-      "bytes": 133880,
-      "lines": 1876
+      "bytes": 134831,
+      "lines": 1890
     },
     {
       "path": "database.py",

docs/governance/stage-17-page-modules.md

@@ -0,0 +1,53 @@
+# Stage 17: Frontend Page Modules and Shared Components
+
+## Scope
+
+This stage establishes frontend feature ownership without changing page markup, API contracts,
+permissions, visual design, or user interaction. The build-free deployment model is retained.
+
+## Page Module Runtime
+
+`static/pages/runtime.js` owns the page lifecycle registry. Each feature registers its views in
+`static/pages/<feature>/page.js` and declares named enter and leave actions. The application
+injects the existing feature functions into that runtime, so page modules do not reach into
+another feature's state or DOM.
+
+The lifecycle boundary now owns:
+
+- page-specific data loading after a successful shell mount;
+- member-aware entry for Screener, Mentor, and Wentian;
+- auction timer cleanup when leaving Auction;
+- canvas, dust, and performance cleanup when leaving Wentian;
+- the internal Screener Tracking view's ownership relationship.
+
+`openView` is now a generic coordinator. It validates the route, asks the page runtime to leave
+the previous page, mounts through the shared shell, and enters the next page. It contains no
+page-name branch chain.
+
+## Shared Components
+
+`static/shared/components.js` is the common rendering boundary for small, stable DOM patterns.
+The first migrated component is the empty state used across market rotation, themes,
+Dragon-Tiger, review, Screener, Wentian history, alerts, entity details, and administration.
+It centralizes escaping and class composition while preserving the exact existing markup.
+
+Collection rendering and text assignment are exposed for later incremental migrations. They
+remain dependency-free and use `XiaobaiUI` for safe escaping.
+
+## Enforcement
+
+Frontend boundary tests verify that:
+
+- shared components load after UI primitives and before page code;
+- the page runtime loads before every feature registration and before `app.js`;
+- every public and internal workspace belongs to exactly one feature page module;
+- `openView` contains no feature-specific view comparisons;
+- shared empty-state rendering is used by multiple feature families;
+- provider requests still exit only through `shared/api.js`.
+
+## Compatibility and Residual Risk
+
+Feature renderers and event handlers still reside in `app.js`; moving them all at once would
+create a high-risk rewrite across already accepted workflows. The new lifecycle and component
+boundaries let those functions move feature by feature later without changing navigation or
+loading behavior. Dedicated mobile composition remains the next governance phase.