feat(quando-91w): initialize project structure and tooling

- Initialize go.mod with module path code.beautifulmachines.dev/quando
- Set Go version to 1.22+ (using 1.25.6)
- Create directory structure (internal/calc/, .github/workflows/)
- Add comprehensive README.md with project overview, features, and examples
- Add MIT LICENSE
- Populate .gitignore for Go projects
- Create GitHub Actions CI workflow for testing, linting, and benchmarking

All acceptance criteria met:
✓ go.mod initialized with correct module path
✓ Go 1.22+ specified in go.mod
✓ Directory structure created
✓ README.md with project overview
✓ LICENSE file (MIT)
✓ .gitignore for Go projects
✓ Basic CI/CD workflow

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2026 quando contributors
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.