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/scripts/gen_app_icons.py

@@ -0,0 +1,115 @@
+#!/usr/bin/env python3
+"""Generates the Android launcher icon and splash screen art from
+../../logo.png (the repo's brand mark + "fuelish" wordmark).
+
+Only the graphic mark (not the wordmark) works as a launcher/splash icon,
+so this first isolates it: crop the upper portion of the source image
+(where the mark lives) and auto-crop that to its actual non-transparent
+bounding box, rather than relying on any hardcoded pixel offsets that
+would break if logo.png is ever redrawn at a different resolution.
+
+Produces:
+- mipmap-<density>/ic_launcher_foreground.png - the mark centered, scaled
+  to the adaptive-icon safe zone (66% of a 108dp canvas), transparent
+  background - paired at runtime with @color/ic_launcher_background (see
+  mipmap-anydpi-v26/ic_launcher.xml, committed - a static reference, not
+  generated) for API 26+.
+- mipmap-<density>/ic_launcher.png / ic_launcher_round.png - the same
+  mark flattened onto ic_launcher_background, for API <26 devices that
+  can't use the adaptive-icon XML at all.
+- drawable-nodpi/splash_icon.png - the mark on a transparent background,
+  referenced by Theme.Fuelish.Splash's windowSplashScreenAnimatedIcon
+  (see values/themes.xml).
+
+Generated output, not committed (see the repo's root .gitignore's
+/android/app/src/main/res/{mipmap-*,drawable-nodpi} entries) - regenerate
+by running this script directly or via Gradle's generateAppIcons task
+(wired into app's preBuild, see ../app/build.gradle.kts). Requires
+Pillow.
+"""
+import os
+import sys
+
+from PIL import Image
+
+SCRIPT_DIR = os.path.dirname(os.path.abspath(__file__))
+LOGO_PATH = os.path.normpath(os.path.join(SCRIPT_DIR, "..", "..", "logo.png"))
+RES_DIR = os.path.normpath(os.path.join(SCRIPT_DIR, "..", "app", "src", "main", "res"))
+
+BACKGROUND_RGBA = (255, 255, 255, 255)  # matches @color/ic_launcher_background
+
+# (density qualifier, adaptive-icon canvas px, legacy launcher px)
+DENSITIES = [
+    ("mdpi", 108, 48),
+    ("hdpi", 162, 72),
+    ("xhdpi", 216, 96),
+    ("xxhdpi", 324, 144),
+    ("xxxhdpi", 432, 192),
+]
+
+# Adaptive icons render only the inner ~66% "safe zone" reliably across
+# launchers that apply their own mask shape.
+SAFE_ZONE_RATIO = 0.66
+
+# Fraction of logo.png's height (from the top) that contains the graphic
+# mark, before the "fuelish" wordmark begins.
+MARK_REGION_HEIGHT_RATIO = 0.60
+
+SPLASH_CANVAS_PX = 480
+SPLASH_ICON_RATIO = 0.75
+
+
+def extract_mark(logo: Image.Image) -> Image.Image:
+    width, height = logo.size
+    region = logo.crop((0, 0, width, round(height * MARK_REGION_HEIGHT_RATIO)))
+    bbox = region.getchannel("A").getbbox()
+    if bbox is None:
+        raise ValueError(f"{LOGO_PATH}: no non-transparent pixels found in the top "
+                          f"{MARK_REGION_HEIGHT_RATIO:.0%} of the image")
+    mark = region.crop(bbox)
+
+    # Pad to square so downstream scaling doesn't distort the aspect ratio.
+    side = max(mark.width, mark.height)
+    square = Image.new("RGBA", (side, side), (0, 0, 0, 0))
+    square.paste(mark, ((side - mark.width) // 2, (side - mark.height) // 2), mark)
+    return square
+
+
+def resized(image: Image.Image, target_px: int) -> Image.Image:
+    ratio = target_px / max(image.width, image.height)
+    size = (round(image.width * ratio), round(image.height * ratio))
+    return image.resize(size, Image.LANCZOS)
+
+
+def centered_on(canvas_px: int, content: Image.Image, background: tuple) -> Image.Image:
+    canvas = Image.new("RGBA", (canvas_px, canvas_px), background)
+    offset = ((canvas_px - content.width) // 2, (canvas_px - content.height) // 2)
+    canvas.paste(content, offset, content)
+    return canvas
+
+
+def main():
+    logo = Image.open(LOGO_PATH).convert("RGBA")
+    mark = extract_mark(logo)
+
+    for density, canvas_px, legacy_px in DENSITIES:
+        mipmap_dir = os.path.join(RES_DIR, f"mipmap-{density}")
+        os.makedirs(mipmap_dir, exist_ok=True)
+
+        foreground = centered_on(canvas_px, resized(mark, round(canvas_px * SAFE_ZONE_RATIO)), (0, 0, 0, 0))
+        foreground.save(os.path.join(mipmap_dir, "ic_launcher_foreground.png"))
+
+        legacy = centered_on(legacy_px, resized(mark, round(legacy_px * SAFE_ZONE_RATIO)), BACKGROUND_RGBA)
+        legacy.convert("RGB").save(os.path.join(mipmap_dir, "ic_launcher.png"))
+        legacy.convert("RGB").save(os.path.join(mipmap_dir, "ic_launcher_round.png"))
+
+    drawable_dir = os.path.join(RES_DIR, "drawable-nodpi")
+    os.makedirs(drawable_dir, exist_ok=True)
+    splash = centered_on(SPLASH_CANVAS_PX, resized(mark, round(SPLASH_CANVAS_PX * SPLASH_ICON_RATIO)), (0, 0, 0, 0))
+    splash.save(os.path.join(drawable_dir, "splash_icon.png"))
+
+    print(f"wrote launcher icons for {len(DENSITIES)} densities + splash icon to {RES_DIR}", file=sys.stderr)
+
+
+if __name__ == "__main__":
+    main()