Initial commit: Complete TDD workshop materials

- Workshop documentation (WORKSHOP_PLAN, FACILITATOR_GUIDE, etc.)
- FizzBuzz kata with demo script (git history to be recreated)
- Password Validator kata with demo script and solution
- Shopping Cart kata with demo script and solution
- Setup guide and TDD reference card for participants

fizzbuzz/README.md

@@ -0,0 +1,56 @@
+# FizzBuzz Kata - Live Demo
+
+## Purpose
+
+This kata is designed for **live demonstration** during the TDD workshop introduction. It shows the RED-GREEN-REFACTOR cycle in a familiar problem that requires minimal explanation.
+
+## The Rules
+
+Write a function that converts numbers to strings according to these rules:
+
+- Numbers divisible by 3 → `"Fizz"`
+- Numbers divisible by 5 → `"Buzz"`
+- Numbers divisible by both 3 and 5 → `"FizzBuzz"`
+- All other numbers → the number as a string (e.g., `"1"`, `"2"`)
+
+## Git History as Teaching Tool
+
+This kata is built with **12 commits** showing each step of the TDD cycle:
+
+```bash
+git log --oneline --all
+```
+
+Each commit shows either:
+- **RED**: A failing test
+- **GREEN**: Minimal code to pass
+- **REFACTOR**: Code cleanup (if needed)
+
+## Using This for the Demo
+
+See `DEMO_SCRIPT.md` for detailed talking points and timing guide.
+
+## Running the Tests
+
+```bash
+dart pub get
+dart test
+```
+
+## Checking Out Individual Steps
+
+To see the code at any point:
+
+```bash
+git log --oneline                    # See all commits
+git checkout <commit-hash>           # Jump to that step
+git checkout main                    # Return to final solution
+```
+
+## The "Aha!" Moment
+
+Notice how the simple tests (1, 2) led to a general solution (n.toString()), and the Fizz/Buzz tests forced the algorithm to emerge naturally. **We never designed the whole solution upfront—the tests revealed it step by step.**
+
+## For Facilitators
+
+This is your warm-up kata. Practice it a few times before the workshop so you can live-code it smoothly while talking through your thinking process.