Improve coverage

[alexander-yevsyukov]

This PR update the code under buildSrc that handles exclusion of generated code from coverage. Now Kotlin files generated by Protobuf compiler are going to be excluded.

Other notable changes

• CoreJvm Compiler was bumped to the latest version which allowed to suppress warnings for the unsigned Protobuf fields using the new DSL from Validation Gradle plugin.

[Copilot]

Pull request overview

This PR updates the buildSrc JaCoCo coverage filtering so generated Kotlin sources (including protoc-gen-kotlin outputs) are excluded from coverage calculations alongside generated Java sources.

Changes:

• Extend source-set discovery to include Kotlin source directories when collecting generated sources for filtering.
• Replace the generated-source → class-name mapping with a unified, path-based approach that supports .kt and .proto.kt, and add unit tests for it.
• Bump snapshot versions and regenerate dependency-report artifacts.

Reviewed changes

Copilot reviewed 11 out of 17 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
version.gradle.kts	Bumps the published snapshot version.
docs/dependencies/pom.xml	Regenerated dependency POM reflecting updated versions.
docs/dependencies/dependencies.md	Regenerated dependency/license report reflecting updated versions and timestamps.
buildSrc/src/test/kotlin/io/spine/gradle/report/coverage/FileExtensionsTest.kt	Adds tests for mapping source files to JVM class names (Java/Kotlin/proto-kt).
buildSrc/src/main/kotlin/io/spine/gradle/report/coverage/PathMarker.kt	Simplifies path markers and renames the output marker for main compilation output.
buildSrc/src/main/kotlin/io/spine/gradle/report/coverage/JacocoConfig.kt	Collects both Java and Kotlin main source dirs for generated-code detection.
buildSrc/src/main/kotlin/io/spine/gradle/report/coverage/FileExtensions.kt	Introduces Kotlin/proto-kt class-name mapping and updates compiled-class parsing marker usage.
buildSrc/src/main/kotlin/io/spine/gradle/report/coverage/FileExtension.kt	Adds the .kt extension constant.
buildSrc/src/main/kotlin/io/spine/gradle/report/coverage/CodebaseFilter.kt	Uses the new Kotlin-aware class-name mapping when excluding generated classes.
buildSrc/src/main/kotlin/io/spine/dependency/local/Validation.kt	Updates the referenced Validation SDK snapshot version.
AGENTS.md	Updates agent/review guidance (config-managed content).
.github/copilot-instructions.md	Updates Copilot guidance (config-managed content).
.agents/skills/review-docs/SKILL.md	Updates doc-review skill guidance (config-managed content).
.agents/skills/kotlin-review/SKILL.md	Updates Kotlin-review skill guidance (config-managed content).
.agents/documentation-guidelines.md	Adds Protobuf header guidance (config-managed content).
.agents/coding-guidelines.md	Adds Kotlin Protobuf DSL guidance (config-managed content).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 9.53%. Comparing base (1918b8f) to head (e7e32a8).
⚠️ Report is 10 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff            @@
##             master    #314   +/-   ##
========================================
  Coverage      9.53%   9.53%           
  Complexity       62      62           
========================================
  Files            82      82           
  Lines          2034    2034           
  Branches        160     160           
========================================
  Hits            194     194           
  Misses         1834    1834           
  Partials          6       6           

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