v2: Initial clean branch with unit tests + CI/CD pipeline

- Started from ac75faa (initial E4B-MarkBase integration)
- Kept Sources/ (all engine code) + Package.swift + .gitignore
- Removed all ad-hoc tests, documentation, scripts, Python files
- Added Tests/00_Unit/ (MathTest, TokenizerTest, SamplerTest)
- Added .gitea/workflows/ci.yaml (build + unit tests + lint)
- Added Scripts/check_resources.sh (memory-aware test runner)
- Added Tests/Manifest.json (resource requirements for all tests)
- Focus: 4-bit quantized models only

.gitignore

@@ -0,0 +1,10 @@
+.build/
+models/
+*.log
+DerivedData/
+.swiftpm/
+Package.resolved
+*.xcodeproj/
+*.xcworkspace/
+.DS_Store
+test_summary.md