fix(plugin-versioning): bump all plugins to 1.0.1 and enforce versio

[necatiozmen]

This PR fixes stale plugin updates by introducing explicit version bumping and enforcement.

What changed

• Bumped all plugin versions from 1.0.0 to 1.0.1 in:
  • .claude-plugin/marketplace.json
  • categories/*/.claude-plugin/plugin.json
• Added CI workflow:
  • .github/workflows/enforce-plugin-version-bump.yml
• Updated contributor guidance:
  • CONTRIBUTING.md with plugin versioning requirements

Why

Users reported that claude plugin update does not pull changed agent markdown files when plugin versions remain unchanged. This caused installed plugins to stay stale even after content updates.

Enforcement added

• If any categories/<category>/*.md file changes, the matching categories/<category>/.claude-plugin/plugin.json version must be bumped.
• Category plugin versions must stay in sync with .claude-plugin/marketplace.json.

Expected outcome

• Content changes are now shipped through normal plugin update flow.
• Future PRs that forget version bumps will fail CI, preventing regressions.

Related issue #73