add gha for mcp_dart_cli

[leehack]

This pull request introduces separate GitHub Actions workflows for the Dart CLI and Core packages, improving CI/CD clarity and maintainability. It adds dedicated test and publish workflows for the CLI, renames and updates the existing workflows for the Core package, and ensures that each workflow only runs for relevant files.

Workflows for the Dart CLI package:

• Added .github/workflows/test_cli.yml to run tests, static analysis, and pana package analysis for the CLI package on PRs and pushes, enforcing a perfect pana score for quality.
• Added .github/workflows/publish_cli.yml to publish the CLI package to pub.dev when a matching tag is pushed.

Workflows for the Core package:

• Renamed and updated .github/workflows/test.yml to .github/workflows/test_core.yml, now only running for Core-related changes and ignoring CLI files.
• Renamed and updated .github/workflows/publish.yml to .github/workflows/publish_core.yml, clarifying that it publishes only the Core package.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 77.44%. Comparing base (6ea9aae) to head (c3d7eb2).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #54   +/-   ##
=======================================
  Coverage   77.44%   77.44%           
=======================================
  Files          40       40           
  Lines        5068     5068           
=======================================
  Hits         3925     3925           
  Misses       1143     1143           

Flag	Coverage Δ
unittests	77.44% <ø> (ø)

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