feat: major heuristic structuring overhaul

- Smart title generation without raw JSON artifacts
- Prompt-based type detection (fix/add/test/refactor/doc)
- Tool-specific fact extraction (tests, git, files, search)
- Human-readable narratives with action arrows
- 10 concept categories (how-it-works, problem-solution, etc.)
- Language detection from path and content
- Git diff deduplication (a/ b/ prefixes)
- Special file support (Makefile, CMakeLists.txt, Dockerfile)
- C/C++ header guard fix (skip #define macros)
- Bump version to 2.0.21

Author: barrelc

mneme/__init__.py

@@ -1,3 +1,3 @@
 """kimi-mneme — Persistent memory for Kimi Code CLI."""
 
-__version__ = "2.0.20"
+__version__ = "2.0.21"