Clean up gamma branch - remove legacy files and fix version

- Remove old quantcli/ package (legacy)
- Remove old setup.py (use pyproject.toml only)
- Fix version: 2.0.0 → 2.0.0-alpha.1 (match __init__.py)
- Now only quantcoder/ package remains
- Modern packaging with pyproject.toml

Author: claude

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "quantcoder-cli"
-version = "2.0.0"
+version = "2.0.0-alpha.1"
 description = "A modern CLI coding assistant for generating QuantConnect trading algorithms from research articles"
 readme = "README.md"
 requires-python = ">=3.10"