chore: add Cloud Agent development environment setup

[msomu]

Summary

Sets up the Cloud Agent development environment for this Android/Kotlin project so ./gradlew build, test, and detekt work out of the box.

The base VM ships JDK 21 and Gradle (via the wrapper) but has no Android SDK, which the build requires. This PR adds:

• .cursor/environment.json — declares the environment and runs the install script (repo-committed, so it is the highest-precedence environment source).
• .cursor/install.sh — an idempotent bootstrap that:
  1. installs the Android command-line tools into /opt/android-sdk (only if missing),
  2. accepts SDK licenses and ensures platform-tools, platforms;android-37.0 (matches compileSdk = 37), and build-tools;37.0.0,
  3. writes local.properties with sdk.dir (git-ignored, machine-specific),
  4. warms the Gradle dependency cache.

No application code is changed. JDK 21 is used as-is (AGP 9.3.1 + Gradle 9.7 support it), matching the base image.

Validation

Check	Result
./gradlew assembleDebug	BUILD SUCCESSFUL — app-debug.apk (~20 MB)
./gradlew build (compile + lint + release)	BUILD SUCCESSFUL — debug + release APKs
./gradlew test	BUILD SUCCESSFUL — unit tests pass
./gradlew detekt	BUILD SUCCESSFUL — no violations
./gradlew build test detekt (full pre-commit gate)	BUILD SUCCESSFUL — 111 tasks
Install idempotence	PASS (re-run ~7s)
Clean install (SDK absent) + build	PASS (~13s provision, then BUILD SUCCESSFUL)
Prebuilt env build + fresh Cloud Agent	PASS — fresh agent booted the build and ran assembleDebug test detekt → BUILD SUCCESSFUL
App data layer vs live API	Fetched 200 todos + a todo detail from jsonplaceholder.typicode.com through the app's real Retrofit/OkHttp/serialization + RepositoryImpl

Note on running the GUI app

The Android app's UI requires an emulator. The x86_64 emulator needs hardware acceleration, but this VM's nested KVM raises a host-kernel kvm_spurious_fault on vCPU creation (the guest never executes), and TCG software emulation is refused for x86_64 images. This is a host virtualization limitation, not fixable from inside the VM. To demonstrate the app actually runs, its core network/data flow was exercised against the live API on the JVM (see validation table).