chore: stage all in-progress work before repo split

Web app: new entities (Image, RenderedAsset, SharedImage, Token,
DeviceImageHistory), enums, repositories, controllers, message handlers,
migrations, tests, frontend upload/library/sticker UI, Vue components.

Firmware: EPD background screen binaries + gen scripts, setup_bg header.

Infra: ddev config, test bundle, gitignore coverage dir.

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

.ddev/config.yaml

@@ -9,6 +9,7 @@ database:
 composer_version: "2"
 webimage_extra_packages:
   - php8.4-imagick
+  - php8.4-pcov
 hooks:
   post-start:
     - exec: composer install --no-interaction 2>/dev/null || true