* proto(driver): drop launcher_activity from LaunchRequest
* refactor(driver): rename Driver to DeviceDriver, drop launcherActivity from Launch
* refactor(driver): rename package maestro to sidecar
* feat(driver): add ChromeDriver backed by chromedp
* feat(hierarchy): replace XML parser with TreeNode JSON parser
* refactor(driver): update mock and runner to DeviceDriver, drop launcherActivity
* feat(runner): add platform routing for web vs sidecar
* test(verifier): update hierarchy fixtures from XML to TreeNode JSON
* feat(sidecar): extract readLogcat/readProcMetrics; add MaestroDriverBackend
- Extract readLogcat() and readProcMetrics() as internal package-level
helpers parameterised by serial
- Add MaestroDriverBackend wiring maestro-client AndroidDriver
- Drop launcherActivity from DriverBackend interface and StubDriverBackend
- Add maestro-utils and micrometer-core as explicit compile deps
* refactor(sidecar): inject DriverBackend into DriverService; drop launcherActivity
- Remove serial and default backend from DriverService constructor
- Make backend a required parameter
- Drop launcherActivity from launch RPC handler
- Create MaestroDriverBackend in Main.kt when platform is android
* test(sidecar): update tests for dropped launcherActivity and required backend
* chore(sidecar): remove unnecessary micrometer-core direct dependency
