feat: add telegram alert workflow and accumulated develop changes

[pphatdev]

Description

This PR promotes the current develop branch to main. The headline change is the addition of a Telegram alert GitHub Action that fires on every push and pull_request against main/master/develop.

• What is being added? .github/workflows/telegram-alert.yml using pphatdev/telegrambot-alert-action@v1.
• Where did it come from? Custom workflow wired to the maintained action.
• Is this fixing anything? No — new capability.

Also bundled in this branch (accumulated since the last develop → main merge): the kfemeetup brand icon, the icon studio workspace under .github/scripts/demo/, PR/issue templates, contributor docs updates, and auto-generated updates to brands.json / regular.json and individual brand JSON files.

Checklist

• New/updated .json icon files placed in the correct category directory (brands/kfemeetup.json, brands/sevenzip.json).
• Filenames use lowercase with hyphens.
• Root brands.json / regular.json were not hand-edited — they were regenerated by the update-category workflow.
• JSON files are valid and follow the schema.
• Followed the CONTRIBUTING.md guide.

Additional Notes

To activate Telegram delivery, add repository secrets TELEGRAM_BOT_TOKEN and TELEGRAM_CHAT_ID under Settings → Secrets and variables → Actions. Without them, the action falls back to posting alerts as PR comments (pushes will silently no-op).