feat: initial project scaffolding

Set up the daena project with:
- pyproject.toml with all core and dev dependencies
- .python-version pinned to 3.13.5
- .gitignore for Python/uv/OS artifacts
- .editorconfig for consistent formatting
- .env.example for deployment configuration
- src/daena package skeleton with version
- uv-managed virtual environment

.env.example

@@ -0,0 +1,5 @@
+# daena configuration
+DAENA_CONFIG_PATH=/etc/daena/daena.yaml
+DAENA_DATA_DIR=/var/lib/daena
+DAENA_LOG_DIR=/var/log/daena
+DAENA_PID_FILE=/run/daena/daena.pid