chore: GPLv3 license + F-Droid packaging (metadata, recipe, guide)

- LICENSE: GNU GPLv3
- fastlane/metadata (de-DE + en-US): title, descriptions, changelog, icon —
  used by both the own F-Droid repo and the official listing
- fdroid/com.scarriffle.calendarr.yml: ready-to-submit fdroiddata build recipe
- FDROID.md: how to run the own repo (fdroid.scarriffle.com) and submit to
  official F-Droid, incl. the signing-key caveat

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

FDROID.md

@@ -0,0 +1,80 @@
+# Publishing Calendarr on F-Droid
+
+Two independent channels — do both in parallel:
+
+- **Own repo (live today):** you build + sign the APK, generate a small catalog,
+  host it at a URL; users add that URL in the F-Droid app.
+- **Official F-Droid (~weeks to be accepted, then automatic):** F-Droid builds +
+  signs from source and lists it in the catalog every F-Droid user already has.
+
+The app is GPLv3 and has **no** non-free dependencies (no Play Services / Firebase),
+so it is F-Droid-eligible. Store-listing metadata lives in `fastlane/metadata/…`.
+
+> ⚠️ Signatures differ between the two channels: your own repo serves APKs signed
+> with **your** keystore; the official build is signed with **F-Droid's** key. A
+> user can't seamlessly update from one to the other (reinstall once). To unify
+> later, set up *Reproducible Builds* so F-Droid ships your signature.
+
+---
+
+## A) Your own repo (fdroid.scarriffle.com)
+
+Needs the `fdroidserver` tool + Android SDK build-tools (for `aapt`).
+
+```bash
+# 1. Install the tool (macOS)
+brew install fdroidserver          # or: pipx install fdroidserver
+
+# 2. Build a SIGNED release APK (uses keystore.properties; F-Droid repos serve
+#    APKs, not AABs)
+./gradlew assembleRelease
+# → app/build/outputs/apk/release/app-release.apk
+
+# 3. Create the repo (once). Generates config.yml + an index-signing key.
+mkdir -p ~/calendarr-fdroid && cd ~/calendarr-fdroid
+fdroid init
+
+# 4. Drop the signed APK in and copy the store metadata
+cp "/path/to/Calendarr Android/app/build/outputs/apk/release/app-release.apk" repo/
+mkdir -p metadata
+# copy the fastlane texts/icons so descriptions show in the client:
+cp -r "/path/to/Calendarr Android/fastlane/metadata/android" metadata/com.scarriffle.calendarr
+
+# 5. Generate/refresh the signed index
+fdroid update -c --pretty
+
+# 6. Upload the whole ~/calendarr-fdroid/repo directory to your webserver at:
+#    https://fdroid.scarriffle.com/fdroid/repo
+```
+
+Users then open F-Droid → Settings → Repositories → **+** →
+`https://fdroid.scarriffle.com/fdroid/repo` → Calendarr appears and auto-updates.
+
+**Each new release:** bump `versionCode`/`versionName` in `app/build.gradle.kts`,
+`./gradlew assembleRelease`, copy the new APK into `repo/`, `fdroid update -c`,
+re-upload. Keep the OLD apks in `repo/` too (users on older versions still update).
+
+---
+
+## B) Official F-Droid (fdroiddata)
+
+Prereqs: the `SourceCode` repo in `fdroid/com.scarriffle.calendarr.yml` must be
+**publicly clonable** (make the Gitea repo public, or mirror to GitHub/GitLab and
+point `Repo:`/`SourceCode:` there), and a signed git tag `v1.1.0` must exist
+(created for this release).
+
+1. Fork <https://gitlab.com/fdroid/fdroiddata>.
+2. Add our recipe as `metadata/com.scarriffle.calendarr.yml`
+   (copy from `fdroid/com.scarriffle.calendarr.yml` in this repo).
+3. Optional local sanity check: `fdroid lint com.scarriffle.calendarr` and
+   `fdroid build -v -l com.scarriffle.calendarr`.
+4. Open a Merge Request. F-Droid reviews, builds and publishes (this first review
+   is the slow part — weeks). Afterwards, `AutoUpdateMode` picks up each new
+   `v<versionName>` tag automatically.
+
+---
+
+## Screenshots (both channels)
+Add PNG/JPG screenshots to
+`fastlane/metadata/android/en-US/images/phoneScreenshots/` (and `de-DE/…`),
+named `1.png`, `2.png`, … They then show on the F-Droid listing.