Rename package and APKs to NilsMG4, credit Fatih, add SPECS.md

- applicationId com.evsuite.abrp -> com.stinnesbeck.nilsmg4 (the car
  build is .unstable); the Java namespace is unchanged. Installs next to
  upstream's app rather than over it.
- APK names NilsMG4-*.apk, debug builds included; build-car follows.
- OTA install-result action, cache/download names, User-Agent and log
  tags follow the new name.
- About credits fatihdonmezdev / FatihsMG4.
- SPECS.md journals what changed and what is still to do, starting
  with pointing the About link and QR code at git.stinnesbeck.com/nils/mg4.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

settings.gradle

@@ -22,7 +22,7 @@ dependencyResolutionManagement {
     }
 }
 
-rootProject.name = "FatihsMG4"
+rootProject.name = "NilsMG4"
 include ':app'
 include ':evhardware'
 project(':evhardware').projectDir = file('EVHardware/lib')