chore(docs): GitHub URLs in README/docs, remove .cursor from repo

Replace git.kalinamall.ru links with github.com/PTah in public docs.
Add Rewrite-GitHostUrls.ps1 and Push-Mirror.ps1 for kalinamall mirror pushes.
Add .cursor/ to .gitignore.

Co-authored-by: Cursor <cursoragent@cursor.com>

docs/event-schema-v1.json

@@ -1,6 +1,6 @@
 {
   "$schema": "https://json-schema.org/draft/2020-12/schema",
-  "$id": "https://git.kalinamall.ru/PapaTramp/security-alert-center/schemas/event-v1.json",
+  "$id": "https://github.com/PTah/security-alert-center/schemas/event-v1.json",
   "title": "Security Alert Center Event v1",
   "description": "Каноническое событие от ssh-monitor или RDP-login-monitor",
   "type": "object",