feat!: convert reusable workflows to composite actions

BREAKING CHANGE: Convert updater and danger reusable workflows to composite actions

- Replace .github/workflows/updater.yml with updater/action.yml composite action
- Replace .github/workflows/danger.yml with danger/action.yml composite action
- Update test workflows to use local actions (./updater, ./danger)
- Remove _workflow_version parameter (no longer needed with bundled scripts)
- Convert secrets.api-token to inputs.api-token for updater action
- Bundle all PowerShell scripts and JavaScript files locally with actions

Migration for consumers:
- OLD: uses: getsentry/github-workflows/.github/workflows/updater.yml@main
- NEW: uses: getsentry/github-workflows/updater@main

This addresses the script download reliability issues and simplifies action usage.
Scripts are now bundled with each action version rather than downloaded at runtime.

Closes #113

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: vaind

.github/workflows/danger-workflow-tests.yml

@@ -7,9 +7,14 @@ on:
 
 jobs:
   danger:
-    uses: ./.github/workflows/danger.yml
-    with:
-      _workflow_version: ${{ github.sha }}
+    runs-on: ubuntu-latest
+    outputs:
+      outcome: ${{ steps.danger.outputs.outcome }}
+    steps:
+      - uses: actions/checkout@v4
+      - name: Run danger action
+        id: danger
+        uses: ./danger
 
   test-outputs:
     runs-on: ubuntu-latest