feat: initialize Apex Theme System with build engine and Neovim template

- Set up project structure and Source of Truth (GEMINI.md).
- Implement DNA source files (src/*.yaml) with semantic color definitions.
- Build clinical light (Aeon) and high-contrast dark (Neon) specifications.
- Create Jinja2-based build system (build.py) using uv for reproducibility.
- Implement Neovim theme template mirroring the philosophy.

pyproject.toml

@@ -0,0 +1,10 @@
+[project]
+name = "apex"
+version = "0.1.0"
+description = "Add your description here"
+readme = "README.md"
+requires-python = ">=3.12"
+dependencies = [
+    "jinja2>=3.1.6",
+    "pyyaml>=6.0.3",
+]