fix(engine): silence Android-target dead-code and unused-import warnings

All 10 warnings were caused by hotkey/keyboard UI code behind
#[cfg(not(target_os = "android"))] call sites whose definitions lacked
the matching gate. Fixes:
- help_plugin: gate keyboard-chip imports and font_kbd; #[allow(dead_code)]
  on ControlRow (keys field is data, not dead)
- hud_plugin/ui_modal: replace cfg shadow pattern with cfg!() expression
  so the hotkey parameter is read on every platform
- home_plugin: gate fn hotkey behind not(android)
- onboarding_plugin: gate HotkeyRow, HOTKEYS, spawn_slide_hotkeys and
  their exclusive imports behind not(android)
- replay_overlay: gate keybind_footer_hint_text behind not(android)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitea/workflows/docker-build.yml

@@ -3,11 +3,13 @@ name: Build and Deploy
 on:
   push:
     branches: [master]
-    # Only run when server code changes, not when CI itself updates deploy/.
-    paths-ignore:
-      - 'deploy/**'
-      - 'argocd/**'
-      - '**.md'
+    paths:
+      - 'solitaire_server/**'
+      - 'solitaire_sync/**'
+      - 'solitaire_core/**'
+      - 'Cargo.toml'
+      - 'Cargo.lock'
+      - '.gitea/workflows/docker-build.yml'
 
 env:
   REGISTRY: git.aleshym.co