docs: complete the docs index and refresh the web interface file tree

docs/README.md's own policy says every page must be linked from the
index, yet five weren't — including the entire skin system
(SKIN_SYSTEM.md, CREATING_SKINS.md), ADAPTIVE_LAYOUT.md,
plugin-safety-harness.md and SPORTS_UNIFICATION.md. Each is now listed
in the section it belongs to, and PLUGIN_ARCHITECTURE_SPEC.md is marked
historical in the index (the doc itself already carries the banner).
web_interface/README.md's static/v3 tree showed only app.css/app.js;
it now reflects the actual contents.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SXb4mKcAkVaxkeTb3YnAdr

docs/README.md

@@ -29,7 +29,7 @@ Start here:
 Going deeper:
 
 - [ADVANCED_PLUGIN_DEVELOPMENT.md](ADVANCED_PLUGIN_DEVELOPMENT.md) — advanced patterns
-- [PLUGIN_ARCHITECTURE_SPEC.md](PLUGIN_ARCHITECTURE_SPEC.md) — full plugin-system spec
+- [PLUGIN_ARCHITECTURE_SPEC.md](PLUGIN_ARCHITECTURE_SPEC.md) — original plugin-system design spec (historical; see its banner for what has drifted)
 - [PLUGIN_DEPENDENCY_GUIDE.md](PLUGIN_DEPENDENCY_GUIDE.md) /
   [PLUGIN_DEPENDENCY_TROUBLESHOOTING.md](PLUGIN_DEPENDENCY_TROUBLESHOOTING.md)
 - [PLUGIN_WEB_UI_ACTIONS.md](PLUGIN_WEB_UI_ACTIONS.md) (+ [example JSON](PLUGIN_WEB_UI_ACTIONS_EXAMPLE.json))
@@ -38,6 +38,8 @@ Going deeper:
 - [PLUGIN_REGISTRY_SETUP_GUIDE.md](PLUGIN_REGISTRY_SETUP_GUIDE.md) (+ [registry template](plugin_registry_template.json))
 - [STARLARK_APPS_GUIDE.md](STARLARK_APPS_GUIDE.md) — Starlark-based mini-apps
 - [widget-guide.md](widget-guide.md) — widget development
+- [ADAPTIVE_LAYOUT.md](ADAPTIVE_LAYOUT.md) — render legibly on any panel size (opt-in font/layout scaling)
+- [plugin-safety-harness.md](plugin-safety-harness.md) — test a plugin across every screen and matrix size
 
 ## Configuring plugins
 
@@ -52,6 +54,8 @@ Going deeper:
 - [ADVANCED_FEATURES.md](ADVANCED_FEATURES.md) — Vegas scroll, on-demand display,
   cache management, background services, permissions
 - [FONT_MANAGER.md](FONT_MANAGER.md) — font system
+- [SKIN_SYSTEM.md](SKIN_SYSTEM.md) — skin architecture for sports scoreboards
+- [CREATING_SKINS.md](CREATING_SKINS.md) — writing and validating a skin
 
 ## Reference
 
@@ -66,6 +70,7 @@ Going deeper:
 - [HOW_TO_RUN_TESTS.md](HOW_TO_RUN_TESTS.md) — running the test suite
 - [MULTI_ROOT_WORKSPACE_SETUP.md](MULTI_ROOT_WORKSPACE_SETUP.md) — multi-repo workspace
 - [MIGRATION_GUIDE.md](MIGRATION_GUIDE.md) — breaking changes between releases
+- [SPORTS_UNIFICATION.md](SPORTS_UNIFICATION.md) — how the sports scoreboard base classes are organized
 
 ## Archive
 

web_interface/README.md

@@ -30,7 +30,12 @@ web_interface/
 └── static/                   # CSS/JS assets
     └── v3/
         ├── app.css
-        └── app.js
+        ├── app.js
+        ├── manifest.json     # PWA manifest
+        ├── plugins_manager.js
+        ├── icons/            # PWA / touch icons
+        ├── js/               # Alpine, htmx, app shell, widgets, utils
+        └── vendor/           # codemirror, fontawesome
 ```
 
 ## Running the Web Interface