docs(retrospective): add Epic 2 retrospective report

Epic 2 Retrospective - Resume Preview Page

Summary:
- 5/5 stories completed (100%)
- All FR5-9, FR15-25 covered
- Modular component architecture delivered
- Successfully adapted to single-column layout change

What Went Well:
- Modular component design enabled easy maintenance
- Rapid architecture adaptation (two-column → single-column)
- Type safety throughout with zero TypeScript errors
- Print mode detection ready for Epic 3

Challenges & Lessons:
- Mid-epic architecture change due to late UX validation
  → Lesson: Run UX validation before tech spec creation
- Missing image property in interface
  → Lesson: Review design templates when creating interfaces
- Inconsistent story context usage
  → Lesson: Decide policy - always or never for small epics

Technical Debt: None

Ready for Epic 3:
- All prerequisites met
- Action items identified for PDF generation
- Dependencies and risks documented

Files:
- docs/sprint-artifacts/epic-2-retrospective.md (created)
- docs/sprint-artifacts/sprint-status.yaml (updated: epic-2-retrospective: completed)

Closes Epic 2 Retrospective

docs/sprint-artifacts/sprint-status.yaml

@@ -53,7 +53,7 @@ development_status:
   2-3-create-resume-header-main-content-components: done
   2-4-create-resume-sidebar-components: done
   2-5-create-download-button-component: done
-  epic-2-retrospective: optional
+  epic-2-retrospective: completed
 
   # ═══════════════════════════════════════════════════════════════
   # Epic 3: PDF Export