Add memba MVP: C++ core, Python SDK, CLI, examples, experiments

C++ core (libmemba.so):
- include/memba/state.h — C API (state_new/free/save/load/get_size)
- src/state.cpp — MEMB file format: magic, version, SHA-256 model_id,
  CRC-32, opaque llama_state_*_data() blob
- src/cli.cpp — minimal demo binary with greedy sampler
- CMakeLists.txt + build.sh with llama.cpp submodule, CUDA auto-detect

Python SDK (memba):
- core.py — file I/O via llama-cpp-python's exposed C functions,
  unwraps _LlamaContext to access raw context pointer (≥0.3.x)
- session.py — high-level Session with auto-save/load, ChatML wrapper
  for instruct models, raw mode for base models
- cli.py — typer-based: chat (REPL), run (one-shot), list, rm, info

Examples:
- 01_basic_save_load.py, 02_chat_session.py

Experiments (throwaway POCs documenting product-direction findings):
- recall_poc.py — git log → state → cross-process query
- mood_poc.py — batch sentiment trajectory, Mamba vs Transformer
- mood_stream_poc.py, mood_batch_poc.py — variants
- diag_saveload.py — minimal save/load isolation test
- README.md documents the headline finding: save/load is byte-identical,
  but Falcon-Mamba-7B-Instruct does not retain facts across conversation
  turns even in-process — limits viable products to single-prompt analysis
  and persona priming.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,45 @@
+# ── Build artifacts ──────────────────────────────────────────────
+build/
+*.o
+*.a
+*.so
+*.so.*
+*.dylib
+*.dll
+CMakeCache.txt
+CMakeFiles/
+cmake_install.cmake
+Makefile
+
+# ── Python ───────────────────────────────────────────────────────
+__pycache__/
+*.py[cod]
+*$py.class
+*.egg-info/
+.pytest_cache/
+.mypy_cache/
+.ruff_cache/
+.venv/
+venv/
+env/
+
+# ── Models (too large for git) ───────────────────────────────────
+*.gguf
+*.safetensors
+
+# ── State files (user data) ──────────────────────────────────────
+*.memb
+.recall/
+
+# ── IDE / editor ─────────────────────────────────────────────────
+.vscode/
+.idea/
+*.swp
+*.swo
+.DS_Store
+
+# ── Claude Code local settings ───────────────────────────────────
+.claude/
+
+# ── OS ───────────────────────────────────────────────────────────
+Thumbs.db