Add scripts/build-version.sh — a single source of truth for the
effective version string:
* HEAD on tag vX.Y.Z -> "X.Y.Z"
* N commits past tag -> "X.Y.Z-N-gSHA"
* working tree dirty -> additional "-dirty" suffix
* no git / no matching tag -> VERSION file fallback
Wired into every packaging path:
* zygisk/build-zip.sh and portshide/build-zip.sh now stage a copy of
module/ and sed-patch `version=` in the staging copy, so committed
module.prop files stay at the last-released version.
* kmod/build-zip.sh now builds into a staging copy too.
* The kmod CI step runs build-version.sh and sed-patches module.prop
before zipping (git installed in the DDK container).
* lsposed/app/build.gradle.kts exec's build-version.sh at configure
time and assigns the result to `versionName` (versionCode stays
static, still bumped by release.py).
All actions/checkout@v6 gained `fetch-depth: 0` so git describe sees
the full tag history inside CI containers.
Result: a locally built or CI-from-main APK shows up in Android
Settings as e.g. `0.6.1-16-gf86e5e5`, and the zip inside carries the
same string in module.prop; the Magisk/KSU manager displays it in the
update list. Release tag builds are indistinguishable from before —
clean `X.Y.Z`. Diagnostic bug reports now carry the exact commit in
the App version line of device_info.txt.
