fix(ci): use snake_case inputs for first-interaction action

[adisusilayasa]

Summary

Fixes CI error in pr-auto-response.yml workflow.

Problem

The actions/first-interaction action requires snake_case input names, but the workflow was using kebab-case:

Error: Input required and not supplied: issue_message

Changes

Before (kebab-case)	After (snake_case)
repo-token	repo_token
issue-message	issue_message
pr-message	pr_message

Testing

The workflow will be tested when this PR is merged and a new contributor opens an issue or PR.

[github-actions]

PR intake checks found warnings (non-blocking)

Fast safe checks found advisory issues. CI lint/test/build gates still enforce merge quality.

• Missing required PR template sections: ## Validation Evidence (required), ## Security Impact (required), ## Privacy and Data Hygiene (required), ## Rollback Plan (required)
• Incomplete required PR template fields: summary problem, summary why it matters, summary what changed, validation commands, security risk/mitigation, privacy status, rollback plan

Action items:

1. Complete required PR template sections/fields.
2. Remove tabs, trailing whitespace, and merge conflict markers from added lines.
3. Re-run local checks before pushing:
   • ./scripts/ci/rust_quality_gate.sh
   • ./scripts/ci/rust_strict_delta_gate.sh
   • ./scripts/ci/docs_quality_gate.sh

Run logs: https://github.com/zeroclaw-labs/zeroclaw/actions/runs/22128369264

Detected blocking line issues (sample):

• none

Detected advisory line issues (sample):

• none

Workflow files changed in this PR:

• .github/workflows/pr-auto-response.yml

Reminder: workflow changes require owner approval via CI Required Gate.

[adisusilayasa]

Superseded by #749 which includes the same fix along with the documentation.