feat: add Tailwind setup and branch/PR workflow scaffolding

.github/pull_request_template.md

@@ -0,0 +1,18 @@
+## Summary
+- 
+
+## Branch
+- Feature branch: `feature/...` or `fix/...`
+- Target branch: `master`
+
+## Validation
+- [ ] `npm run build` passes locally
+- [ ] Manual smoke test completed
+
+## Hermes Dev Review
+- [ ] I reviewed changed files for edge cases/regressions
+- [ ] I verified no unrelated changes are included
+- [ ] I left follow-up TODOs only when necessary
+
+## Notes for reviewer
+- 

docs/DEVELOPMENT_WORKFLOW.md

@@ -0,0 +1,29 @@
+# ContractionCounter Development Workflow
+
+## Branch-first flow
+
+1. Sync latest `master`:
+   - `git checkout master`
+   - `git pull origin master`
+2. Create a focused branch:
+   - `git checkout -b feature/<short-name>`
+3. Implement in small commits.
+4. Run quality gate:
+   - `npm run build`
+5. Push branch:
+   - `git push -u origin <branch>`
+6. Open PR to `master`.
+
+## Review standard (Hermes Dev)
+
+Before opening PR, perform self-review on:
+- Correctness and edge cases
+- Regression risk
+- Clarity/readability
+- Scope control (no unrelated edits)
+
+## PR/MR expectations
+
+- One problem per branch
+- Clear summary and validation notes
+- Keep PRs small enough to review quickly