Add UnrealDocGenerator tool and UE API skill

- ue_parser.py: position-based UE C++ header parser
- ue_markdown.py: compact agent-optimised Markdown renderer
- generate.py: two-pass CLI (parse-all → type index → render-all)
- samples/: representative UE headers (GeomUtils, AIController, GameplayTagsManager)
- .claude/skills/ue-api/: Claude Code skill for querying UE docs + source headers
- CLAUDE.md: architecture notes, usage, critical gotchas

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

.claude/plugins/ue-api/.claude-plugin/plugin.json

@@ -0,0 +1,5 @@
+{
+  "name": "ue-api",
+  "description": "Unreal Engine API documentation skill — queries generated docs and source headers to answer questions about UE C++ APIs, class hierarchies, and system flows.",
+  "version": "1.0.0"
+}