Integrate symbols/ into main repo

- Added symbols/ folder (previously separate repo)
- Removed symbols/ from .gitignore
- Updated CLAUDE.md documentation
- Deleted separate Symbols repo on Gitea

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

symbols/.gitignore

@@ -0,0 +1,11 @@
+# OS files
+.DS_Store
+Thumbs.db
+
+# IDE
+.vscode/
+.idea/
+
+# Temporary files
+*.tmp
+*.bak