docs: correct semantically stale content across the user and developer guides

A second-pass content audit checked the guides' substantive claims
against the code (the first pass only fixed mechanical drift). Fixes:

- GETTING_STARTED: described booting a prebuilt SD image and seeing
  default clock/weather plugins — neither exists. Now documents the real
  install (Pi OS Lite + one-shot installer / first_time_install.sh) and
  that displays come from the Plugin Store. Duration and ordering
  instructions moved to the Rotation tab where the controls actually
  live.
- WEB_INTERFACE_GUIDE: three whole tabs were undocumented (Rotation,
  Backup & Restore, Tools) and the Display tab's Vegas Scroll section
  was unmentioned. Fonts overrides are per display element (not per
  plugin); Logs has an Auto-scroll checkbox (not a Pause button); the
  aspirational keyboard-shortcut list and no-JS claim removed.
- TROUBLESHOOTING: the hand-written service-file template (wrong user,
  wrong ExecStart, dropped the autostart gate) replaced with the real
  systemd/ units + install scripts; recovery steps no longer copy
  placeholder units verbatim; WiFi curl endpoint corrected to /api/v3/;
  cache-clearing advice now targets the real cache locations.
- ADVANCED_FEATURES: removed a false claim that CacheManager has no
  delete(); fixed two example snippets that raise TypeError
  (BackgroundDataService and get_config_file_mode signatures); fixed
  cache paths, a 5-minute TTL that is actually 1 hour, and the vegas
  table now links the complete 26-key reference.
- EMULATOR_SETUP_GUIDE: documented run.py flags that don't exist
  (--plugin/--test-plugins) removed in favor of dev_server.py and
  check_plugin.py; shipped emulator config values corrected (browser
  adapter default on :8888, not pygame).
- PLUGIN_QUICK_REFERENCE: drag-and-drop reordering is shipped, not
  'not yet supported'; discovery-fallback and registry-repo claims
  corrected. PLUGIN_API_REFERENCE: get_vegas_segment_width returns
  panels, not pixels. CONTRIBUTING: the repo uses flake8/mypy/bandit
  pre-commit hooks, not black/ruff, and tests need requirements-test.txt.
- SKIN_SYSTEM/DEVELOPER_QUICK_REFERENCE: stale module paths.

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

docs/WEB_INTERFACE_GUIDE.md

@@ -39,12 +39,18 @@ present:
 - **WiFi** — Network selection and AP-mode setup
 - **Schedule** — Power and dim schedules
 - **Display** — Matrix hardware configuration (rows, cols, hardware
-  mapping, GPIO slowdown, brightness, PWM)
+  mapping, GPIO slowdown, brightness, PWM) and Vegas Scroll Mode
+  settings
+- **Rotation** — drag-and-drop **Rotation Order** list and per-plugin
+  **Screen Durations**
 - **Config Editor** — Raw `config.json` editor with validation
+- **Backup & Restore** — back up and restore your configuration
 - **Fonts** — Upload and manage fonts
 - **Logs** — Real-time log streaming
 - **Cache** — Cached data inspection and cleanup
 - **Operation History** — Recent service operations
+- **Tools** — system diagnostics, git & updates, Python dependencies,
+  maintenance, power supply, network radio, services, and plugin health
 
 A second nav row holds plugin tabs:
 
@@ -111,6 +117,12 @@ Configure your LED matrix hardware:
 - Dynamic Duration — global cap for plugins that extend their display
   time based on content
 
+**Vegas Scroll Mode:** the Display tab also has a full Vegas Scroll
+Mode section — enable toggle, scroll speed, separator width, dynamic
+duration, and related settings — so you can configure Vegas mode
+entirely from the web UI without hand-editing JSON. See
+[ADVANCED_FEATURES.md](ADVANCED_FEATURES.md) for what the options do.
+
 Changes require **Restart Display Service** from the Overview tab.
 
 ### Plugin Manager Tab
@@ -159,9 +171,10 @@ Manage fonts for your display:
 - See font previews
 - Check font sizes and styles
 
-**Plugin Font Overrides:**
-- Set custom fonts for specific plugins
-- Override default font choices
+**Font Overrides:**
+- Overrides are set per display *element* (e.g. a specific score or
+  clock text element), not per plugin
+- Override default font choices for individual elements
 - Preview font changes
 
 **Delete Fonts:**
@@ -183,9 +196,11 @@ View real-time system logs:
 - Filter by plugin or component
 
 **Actions:**
+- **Refresh**: Reload the log view
 - **Clear**: Clear the current view
 - **Download**: Download logs for offline analysis
-- **Pause**: Pause auto-scrolling
+- **Auto-scroll** checkbox: toggle automatic scrolling to the latest
+  entries
 
 ---
 
@@ -248,7 +263,8 @@ The web interface uses Server-Sent Events (SSE) for real-time updates:
 **Performance:**
 - Minimal bandwidth usage
 - Server-side rendering for fast load times
-- Progressive enhancement - works without JavaScript
+- The UI is built on Alpine.js and HTMX, so JavaScript must be enabled
+  in the browser
 
 ---
 
@@ -267,17 +283,6 @@ The interface is fully responsive and works on mobile devices:
 
 ---
 
-## Keyboard Shortcuts
-
-Use keyboard shortcuts for faster navigation:
-
-- **Tab**: Navigate between form fields
-- **Enter**: Submit forms
-- **Esc**: Close modals
-- **Ctrl+F**: Search in logs
-
----
-
 ## API Access
 
 The web interface is built on a REST API that you can access programmatically:
@@ -288,7 +293,7 @@ http://your-pi-ip:5000/api/v3
 ```
 
 The API blueprint mounts at `/api/v3` (see
-`web_interface/app.py:144`). All endpoints below are relative to that
+`web_interface/app.py:199`). All endpoints below are relative to that
 base.
 
 **Common Endpoints:**