fix: complete workflow fixes for Claude Code action on master

[lgallard]

Summary

Completes the workflow fixes for the Claude Code action on master branch that were missing from the previous merge.

Problem

The previous PR merge didn't include all the necessary fixes, causing the workflow to fail on master with the same original errors:

• "Tag mode cannot handle workflow_dispatch events"
• GitHub authentication issues

Solution

Applied all 4 required fixes to the workflow:

✅ Fixes Applied

1. OIDC Permissions: id-token: write (already present)
2. GitHub Token Environment: GITHUB_TOKEN: ${{ secrets.TERRAFORM_AUTOMATION_TOKEN }}
3. Agent Mode: mode: agent parameter for workflow_dispatch support
4. GitHub Token Parameter: github_token: ${{ secrets.TERRAFORM_AUTOMATION_TOKEN }}

Test Plan

• Pre-commit checks passed
• Test workflow on master after merge
• Verify both Claude Code execution and git push work correctly

Changes

env:
  CLAUDE_TOKEN: ${{ secrets.CLAUDE_CODE_OAUTH_TOKEN }}
+ GITHUB_TOKEN: ${{ secrets.TERRAFORM_AUTOMATION_TOKEN }}
with:
  claude_code_oauth_token: ${{ env.CLAUDE_TOKEN }}
+ mode: agent
+ github_token: ${{ secrets.TERRAFORM_AUTOMATION_TOKEN }}

Closes #224 (for real this time)