Phase 5: Testing & documentation refinement post-migration

[jessefreeman]

Scope:
Enhance testing, finalize documentation, and remove residual CoffeeScript artifacts after migration phases complete.

Key Actions:

• Add/expand Jest tests for core logic and API endpoints
• Verify type coverage & consider enabling stricter compiler flags
• Remove any lingering compiled CoffeeScript JS duplicates
• Update README & developer docs with new build/run steps
• Add migration retrospective section summarizing metrics improvement

Acceptance Criteria:

• Jest suite passes in CI
• No .coffee files remain
• README reflects TypeScript workflow only
• Documented metrics: before vs after file counts, LOC typed

Risks:

• Test gaps discovered late → allocate buffer time

[jessefreeman]

Parent epic: #6