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>

.env

@@ -45,4 +45,10 @@ MESSENGER_TRANSPORT_DSN=doctrine://default?auto_setup=0
 
 ###> symfony/mailer ###
 MAILER_DSN=null://null
+MAILER_SENDER=noreply@pictureframe.edholm.me
 ###< symfony/mailer ###
+
+###> pictureframe ###
+SHARE_TOKEN_TTL_DAYS=7
+HARD_DELETE_TOKEN_TTL_DAYS=30
+###< pictureframe ###