feat: expose native pattern capabilities

[jbachorik]

Summary

Exposes explicit immutable capabilities for native named-LTS compiled patterns:

• native-only execution;
• native-algorithm linearity, scoped to caller-controlled sequence cost;
• caller-thread cooperative interruptible CharSequence matching.

The capability set is stable across direct compilation, bounded-cache hits, eviction/recompile, and independent compiler instances.

Validation

• ./gradlew :reggie-runtime:test --tests com.datadoghq.reggie.runtime.ReggieNativeCapabilityTest --tests com.datadoghq.reggie.runtime.InterruptibleCharSequenceTest
• ./gradlew :reggie-runtime:test
• ./gradlew spotlessApply
• final implementation-plan validation: clean
• final independent code review: clean

[Copilot]

Pull request overview

This PR introduces an explicit, immutable “capabilities” surface for native named-LTS compiled patterns, and extends tests to ensure those capabilities remain stable across compilation paths and that interruptibility checks execute on the caller thread.

Changes:

• Add ReggieNativeCapability enum to represent guaranteed properties of native named-LTS patterns.
• Expose ReggieCompiledPattern.capabilities() returning a shared immutable capability set.
• Add/extend runtime tests covering capability stability (direct compile, cached compile, eviction/recompile, separate compiler instances) and verifying interrupt checks run on the matching caller thread.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
reggie-runtime/src/main/java/com/datadoghq/reggie/runtime/ReggieNativeCapability.java	Defines the stable capability enum and documents interruptibility/linearity guarantees.
reggie-runtime/src/main/java/com/datadoghq/reggie/runtime/ReggieCompiledPattern.java	Exposes an immutable capability set via capabilities().
reggie-runtime/src/test/java/com/datadoghq/reggie/runtime/ReggieNativeCapabilityTest.java	Adds coverage for capability immutability and stability across caching/eviction/compiler instances.
reggie-runtime/src/test/java/com/datadoghq/reggie/runtime/InterruptibleCharSequenceTest.java	Adds a test asserting interruption checks run on the matching caller thread.

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