Add ChartPuck Circle and Droste Zoom math notebooks (#48)

## Summary
- Add **ChartPuck Circle** notebook: an interactive complex-plane
mapping explorer (inspired by 3Blue1Brown) where users drag a puck to
see how circles transform under z², 1/z, Joukowski, exp, and log.
- Add **Droste Zoom** notebook: a Droste effect simulator using
log-polar transforms and complex multiplication, with paint widget
support and multiple view modes.
- Update README with entries for both notebooks and generate session
metadata.

## Test plan
- [x] `uvx marimo check` passes on both notebooks
- [x] `uv run scripts/validate-sessions.py` passes
- [ ] README molab badge links are correct

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: koaning

README.md

@@ -112,6 +112,8 @@ uvx marimo edit --sandbox <notebook>
 | Thermodynamic Linear Algebra | Estimate a matrix inverse via overdamped Langevin dynamics. | [![Open in molab](https://marimo.io/molab-shield.svg)](https://molab.marimo.io/github/marimo-team/gallery-examples/blob/main/notebooks/math/thermodynamic_linear_algebra.py/wasm) |
 | Interactive ODE Solver | Drag to set initial conditions and explore solutions of an ODE with a direction field. | [![Open in molab](https://marimo.io/molab-shield.svg)](https://molab.marimo.io/github/marimo-team/gallery-examples/blob/main/notebooks/math/ode-solver.py) |
 | RPSLS Math | Explore balanced tournament graphs for Rock-Paper-Scissors variants. | [![Open in molab](https://marimo.io/molab-shield.svg)](https://molab.marimo.io/github/marimo-team/gallery-examples/blob/main/notebooks/math/rpsls-math/notebook.py) |
+| ChartPuck Circle | Explore how complex functions transform circles interactively. | [![Open in molab](https://marimo.io/molab-shield.svg)](https://molab.marimo.io/github/marimo-team/gallery-examples/blob/main/notebooks/math/chartpuck-circle.py) |
+| Droste Zoom | Simulate the Droste zoom effect with log-polar transforms. | [![Open in molab](https://marimo.io/molab-shield.svg)](https://molab.marimo.io/github/marimo-team/gallery-examples/blob/main/notebooks/math/zooming.py) |
 
 ## Custom UI elements with Anywidget