feat: Add content filtering

[yllkryeziu]

Summary

• Detects sensitive content (API keys, JWT tokens, private keys, connection strings) and replaces with
  placeholders
• Adds .crowdcodeignore file for gitignore-style file filtering with auto-detection of existing sensitive files
• Shows throttled notifications (once per session) when sensitive content is filtered

Key Changes

• src/security.ts: New security module with sensitive content patterns and file filtering logic
• src/recording.ts: Integrated content filtering
• src/extension.ts: Added security commands and initialization
• src/actionsProvider.ts: Added "Open .crowdcodeignore" action