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

AGENTS.md

@@ -0,0 +1,40 @@
+# Agent Instructions
+
+This project uses **bd** (beads) for issue tracking. Run `bd onboard` to get started.
+
+## Quick Reference
+
+```bash
+bd ready              # Find available work
+bd show <id>          # View issue details
+bd update <id> --status in_progress  # Claim work
+bd close <id>         # Complete work
+bd sync               # Sync with git
+```
+
+## Landing the Plane (Session Completion)
+
+**When ending a work session**, you MUST complete ALL steps below. Work is NOT complete until `git push` succeeds.
+
+**MANDATORY WORKFLOW:**
+
+1. **File issues for remaining work** - Create issues for anything that needs follow-up
+2. **Run quality gates** (if code changed) - Tests, linters, builds
+3. **Update issue status** - Close finished work, update in-progress items
+4. **PUSH TO REMOTE** - This is MANDATORY:
+   ```bash
+   git pull --rebase
+   bd sync
+   git push
+   git status  # MUST show "up to date with origin"
+   ```
+5. **Clean up** - Clear stashes, prune remote branches
+6. **Verify** - All changes committed AND pushed
+7. **Hand off** - Provide context for next session
+
+**CRITICAL RULES:**
+- Work is NOT complete until `git push` succeeds
+- NEVER stop before pushing - that leaves work stranded locally
+- NEVER say "ready to push when you are" - YOU must push
+- If push fails, resolve and retry until it succeeds
+