Add Eclipse release compatibility matrix workflow with parameterized target platform resolution

[Copilot]

This introduces a dedicated compatibility CI workflow to validate the plugin against Eclipse releases from 2024‑06 through 2026‑03 without modifying source files per release. It also parameterizes Tycho target resolution so compatibility checks can switch target files and EE constraint behavior via Maven properties.

• Compatibility CI matrix

  • Added .github/workflows/compatibility.yml with a Windows matrix for:
    • 2024-06, 2024-09, 2024-12, 2025-03, 2025-06, 2025-09, 2025-12, 2026-03
  • Maven invocation now passes quoted properties to avoid PowerShell splitting:
    • target.platform.file
    • target.resolve.with.ee.constraints
  • EE constraints are enabled for 2024-* and disabled for 2025-03+ targets.

• Target platform files

  • Added targets/*.target for all matrix versions above.
  • Each target keeps the same IU set as current baseline:
    • org.eclipse.platform.feature.group
    • org.eclipse.jdt.feature.group
  • Repository URL is version-specific under https://mirrors.aliyun.com/eclipse/releases/<version>/.

• Baseline target indirection

  • Updated root target-platform.target to include targets/2024-06.target via a nested Target location, keeping baseline definition centralized and reusable.

• Tycho Maven parameterization

  • Updated root pom.xml to add:
    • target.platform.file (default: target-platform.target)
    • target.resolve.with.ee.constraints (default: true)
  • Wired both into target-platform-configuration:
    • <file>../../${target.platform.file}</file>
    • <resolveWithExecutionEnvironmentConstraints>${target.resolve.with.ee.constraints}</resolveWithExecutionEnvironmentConstraints>

Example workflow command pattern:

run: mvn -B clean verify -ntp "-Dtarget.platform.file=targets/${{ matrix.target }}.target" "-Dtarget.resolve.with.ee.constraints=${{ startsWith(matrix.target, '2024-') && 'true' || 'false' }}"