feat(app): what's new after an update, drafted by the release tool (ADR 0030, D61)

halkyon_app's WhatsNew reads what each release changed from the app's
assets/whats_new/ (<version>.<language>.txt, English and German, a change
a line): after an update a sheet lists every release since the one the
device showed last, newest first, once; Settings shows the running
version's again, above About. Nothing on a fresh install.

tool/release.dart drafts the missing texts from the commits that count
after "Go on?" (German marked TRANSLATE:), opens them in the editor until
they fit (no mark left, F-Droid's 500 characters) and commits them with
the version. The English is the Forgejo notes' What's new, each language
F-Droid's changelog of the build, written at publishing and copied in by
tool/fdroid_repo.sh. Learn and Train bundle their texts, Learn's 0.22.0
and Train's 0.1.0 written to start.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

tool/fdroid_repo.sh

@@ -114,6 +114,12 @@ restore() {
 restore repo
 restore archive
 cp -r tool/release/fdroid/. "$working/"
+# What's new in the release as each language's changelog of its build
+# (metadata/<app id>/<locale>/changelogs/<build>.txt), which tool/release.dart
+# writes from the app's texts and names here; kept in the working folder after.
+if [ -n "${HALKYON_FDROID_METADATA:-}" ]; then
+  cp -r "$HALKYON_FDROID_METADATA/." "$working/metadata/"
+fi
 # fdroid refuses a config.yml others can read.
 chmod 600 "$working/config.yml"
 # Each app's own icon in the F-Droid app (the repository's is the kingfisher,