Update .gitignore: exclude plugin build artifacts and local Claude settings

Keeps existing ignores intact. Adds:
- Plugin Binaries/ and Intermediate/ (generated on first compile)
- *.sln / *.suo (generated by UE project regeneration)
- .claude/settings.local.json (machine-specific, not shared)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.claude/settings.local.json

@@ -1,7 +0,0 @@
-{
-  "permissions": {
-    "allow": [
-      "Bash(dir /s \"E:\\\\ASTERION\\\\GIT\\\\PS_AI_Agent\")"
-    ]
-  }
-}