Migrate all components to TypeScript

[daedalist]

Effort: Medium (2-4 hours)
Impact: Full type safety across codebase
Phase: Long-Term

Current State

Components use .jsx and .js, while app files use .tsx

Files to migrate

• src/components/Header.jsx
• src/components/CandidateList.jsx
• src/components/Ghostbook.jsx
• src/components/Ghost.jsx
• src/components/ObservationList.jsx
• src/lib/evidenceState.js
• src/lib/evidence.js

Pros

• Better type safety and IntelliSense
• Catch bugs at compile time
• Consistent codebase (currently mixed)
• Easier refactoring

Cons

• Initial time investment to add types
• May need to define interfaces for ghost data

Risks

Low - TypeScript already configured, just need to rename and add types

Implementation

1. Create type definitions for ghost data (interfaces)
2. Rename .jsx → .tsx and .js → .ts
3. Add type annotations for props and state
4. Fix any type errors