Add manual workflow for auto-commit and push

[Copilot]

Implements a manually-triggered GitHub Actions workflow to commit and push repository changes on demand.

Implementation

• Workflow trigger: workflow_dispatch with optional commit message input
• Change detection: Checks for uncommitted changes before attempting commit
• Security hardening:
  • Explicit contents: write permission scope
  • Commit message passed via environment variable to prevent injection
  • Explicit branch reference in push operation

Files Added

• .github/workflows/auto-push.yml - Main workflow implementation
• .github/workflows/README.md - Usage documentation (Vietnamese/English)

Workflow Behavior

on:
  workflow_dispatch:
    inputs:
      commit_message:
        default: 'Auto-update data'

Executes: git add . && git commit && git push origin ${{ github.ref }}

Only commits when changes are detected; provides clear status feedback otherwise.

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