Interactive dashboard with a typed data layer

• Map every rubric criterion to a file, test, or artifact.
• Include reproducible install, run, and verification commands.
• Record one meaningful decision, alternatives, and tradeoffs.
• Show representative output and state known limitations.

# Interactive dashboard with a typed data layer

## Goal
A TypeScript dashboard (any framework) over a public API: typed fetch layer, loading/error/empty states, client-side caching, at least one chart, and unit tests for the data layer.

## Acceptance criteria
- [ ] Type safety: Strict TS; API responses validated at the boundary.
- [ ] State handling: Loading/error/empty handled everywhere data renders.
- [ ] Tests: Data layer unit-tested incl. failure paths.
- [ ] Code organization: Clear module boundaries; no god components.

## Verification
- [ ] Document installation and run commands.
- [ ] Record automated checks and their exact commands.
- [ ] Add representative output, screenshots, or a short demo where useful.
- [ ] Confirm failure paths and known constraints.

## Decision log
### Decision title
- Context:
- Choice:
- Alternatives considered:
- Tradeoffs:

## Evidence
- Link each rubric criterion to the file, test, or artifact that demonstrates it.

## Known limitations
- List what is intentionally out of scope and what should be improved next.