Add HTTP API server, Android app, and CI build/publish pipeline

- docker-compose.yml + tooling-container/src/server.py: serve
  preprocess/OCR/extract over an async job API (POST /jobs, GET
  /jobs/{id}) instead of manual host-script runs per receipt
- android/: Kotlin/Compose app - capture a receipt photo, poll job
  progress, review/edit extracted fields, save locally (Room), export
  to CSV/ODS
- .gitea/workflows/build.yml: build the debug APK and publish it to
  dl.ladkau.de on push
- build-image.sh: also pull ollama/ollama so all pipeline images are
  ready after one script
- add project logo (also used for the app's launcher icon/splash)

android/app/src/main/res/values/themes.xml

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <style name="Theme.Fuelish" parent="android:Theme.Material.Light.NoActionBar" />
+
+    <style name="Theme.Fuelish.Splash" parent="Theme.SplashScreen">
+        <item name="windowSplashScreenBackground">@color/splash_background</item>
+        <item name="windowSplashScreenAnimatedIcon">@drawable/splash_icon</item>
+        <item name="postSplashScreenTheme">@style/Theme.Fuelish</item>
+    </style>
+</resources>