docs(android): Gradle 9 compatibility for the Gradle plugin

[krassx]

Adds a Gradle 9 section to docs/sdk/android/gradle-plugin/requirements.mdx. A customer reported the plugin "isn't compatible with Gradle 9". That's true only for plugin 4.0.0 – 4.0.2, and the page didn't say so.

Changes

• Requirements table: the Gradle row now notes that Gradle 9 needs plugin 4.0.3+.
• New "Gradle 9" section:
  • a plugin × Gradle 8/9 matrix;
  • the exact configuration-time error from 4.0.0 – 4.0.2 (ProjectDependency.getDependencyProject()), so customers searching for it land here;
  • "upgrade to the latest release" as the fix.
• "Verified combinations": the Gradle/AGP pairs built with plugin 4.0.7, and whether configuration cache was exercised. 4.0.3 – 4.0.6 were also verified on Gradle 9.8.0 + AGP 9.4.1.
• "AGP 9 and Kotlin": applying org.jetbrains.kotlin.android on AGP 9 fails with Cannot add extension with name 'kotlin', with or without Bugsee. The section links Google's AGP–Gradle compatibility table.

Every claim comes from builds I ran with the published plugin (R8 release builds, checking instrumentation, BUILD_UUID injection and the mapping upload). cspell and npm run build pass locally.

Not changed: the installation snippets in docs/sdk/android/installation.mdx still apply org.jetbrains.kotlin.android, which breaks on AGP 9. That belongs in a separate PR.

Companion change to the plugin README is in bugsee/bugsee-android-gradle-plugin.

🤖 Generated with Claude Code

[krassx]

Companion plugin README PR: bugsee/bugsee-android-gradle-plugin#6