fix(roaming): live coords from shared flow, marker by locator pair, versioned apk

Addresses three review findings:

1. Coordinates now come straight from settingsRepo.stationPosition in the screen (collectAsStateWithLifecycle) — the exact same StateFlow the Settings page shows. Previously a separate ViewModel re-derived them, and it could lag behind the Settings page (user: '设置页更新了站位但漫游页死活不更新'). With the shared source the two pages can never disagree. RoamingViewModel removed; state derivation moved to RoamingState.fromPosition().

2. Red marker placement ported faithfully from the QTH定位器 app: it is driven by the 3rd character pair of the 8-char locator (the 'ih' in OL42ih45), mapped to a 0..1 fraction (lon a=west..x=east, lat inverted a=south..x=north), then scaled to the actual center-cell size. The grid now uses the reference proportions (columns 21.4/56.2/21.4, rows 31.5/35.9/31.7) and fills the screen, so the marker lands accurately on any device.

3. Workflow now uploads a versioned APK (look4sat-<version>.apk instead of look4sat.apk).

Also: Settings 'Other' card rows got vertical spacing (Arrangement.spacedBy) so the new roaming toggle is not glued to the night-mode row.

.github/workflows/release.yml

@@ -39,19 +39,22 @@ jobs:
         run: |
           echo "${{ secrets.KEY_STORE }}" | base64 -d > keystore.jks
           APK=$(find app/build/outputs/apk/release -name "*.apk" | head -1)
+          VERSION=${TAG_NAME#v}
+          SIGNED_APK="app/build/outputs/apk/release/look4sat-${VERSION}.apk"
           BUILD_TOOLS=$(ls -d ${ANDROID_HOME}/build-tools/*/ | sort -V | tail -1)
           ${BUILD_TOOLS}apksigner sign \
             --ks keystore.jks \
             --ks-pass pass:${{ secrets.KEY_STORE_PASSWORD }} \
             --ks-key-alias ${{ secrets.KEY_ALIAS }} \
             --key-pass pass:${{ secrets.KEY_PASSWORD }} \
-            --out app/build/outputs/apk/release/look4sat.apk \
+            --out "$SIGNED_APK" \
             "$APK"
           rm keystore.jks
+          echo "SIGNED_APK=$SIGNED_APK" >> "$GITHUB_ENV"
 
       - name: Create Release
         env:
           GH_TOKEN: ${{ github.token }}
         run: |
           gh release create $TAG_NAME --title=$TAG_NAME --generate-notes
-          gh release upload $TAG_NAME app/build/outputs/apk/release/look4sat.apk
+          gh release upload $TAG_NAME "$SIGNED_APK"