Preparation for release v2.0.0

[thebinaryfelix]

What was done

Bug fixes

• Fixed ignore_case default value in action.yml from false to true, aligning it with the documented behaviour in the README
• Fixed ignore_case and follow_symlinks default values from YAML booleans to strings, as required by the GitHub Actions input schema
• Fixed typo in ignore_case input description

CI / Infrastructure

• Upgraded actions/checkout from v1 to v4 and actions/setup-node from v3 to v4 in all workflows
• Updated Node.js version from 22 to 24 across all workflows to match the node24 runtime declared in action.yml
• Added yarn build before npx release-it in the release script to ensure dist/ is always up-to-date at release time

Documentation

• Added a "Releasing a New Version" section to the README with step-by-step instructions for the local release process, including build, yarn release, and optional major tag update
• Added troubleshooting note for the No upstream configured for current branch error
• Replaced hardcoded @v1 references in README examples with @vX.X.X placeholder

Tests

• Added 5 missing unit tests for checkFileExistence, which previously had no coverage:
  • getBooleanInput called with correct input names (Inputs.NO_CASE, Inputs.FOLLOW)
  • Resolves true/false based on glob results
  • Rejects on glob error
  • nocase and follow options correctly forwarded to glob

Config

• Removed **/*.test.ts from tsconfig.json exclude so the TypeScript language server correctly resolves the ~/* path alias in test files

Also closes #7