Skip empty doc files and prune dead type-index entries

- render_header() returns "" when a header has no documented content
  (no /** */ comments on any class, property, function, enum, or delegate)
- generate.py skips writing those files and tracks which were written
- type-index.txt is filtered to only include types from written files,
  preventing dead entries that would cause get_class_overview to fail
- Summary line now reports how many files were skipped

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

README.md

@@ -5,8 +5,8 @@ Generates compact, agent-readable Markdown documentation from Unreal Engine C++
 ## How it works
 
 1. **Parse** — `docgen/ue_parser.py` scans UE headers into dataclasses using a position-based scanner (handles nested braces, macros, delegates, namespaces).
-2. **Render** — `docgen/ue_markdown.py` emits one `.md` per header: only items with C++ doc comments, no deprecated functions, compact enum format.
-3. **Index** — `docgen/generate.py` produces `type-index.txt`: a flat `TypeName: path/to/File.md` lookup for instant type resolution.
+2. **Render** — `docgen/ue_markdown.py` emits one `.md` per header: only items with C++ doc comments, no deprecated functions, compact enum format. Headers with no documented content produce no output file.
+3. **Index** — `docgen/generate.py` produces `type-index.txt`: a flat `TypeName: path/to/File.md` lookup for instant type resolution. Only types from files that were actually written are indexed.
 4. **Serve** — `ue_mcp_server.py` exposes the docs to Claude as callable MCP tools.
 
 ## Usage