docs(02-03): complete app integration plan — Phase 2 all 3 plans done

- Create 02-03-SUMMARY.md documenting DocumentState, scrolling, status bar, error screen
- Update STATE.md: Phase 2 complete, 6 total plans, Phase 3 next
- Update ROADMAP.md: Phase 2 all 3 plans SUMMARY present, marked Complete
- Mark NAV-05, NAV-08, NAV-09 requirements complete in REQUIREMENTS.md

.planning/REQUIREMENTS.md

@@ -33,11 +33,11 @@ Requirements for initial release. Each maps to roadmap phases.
 - [ ] **NAV-02**: User can follow standard `[text](path.md)` links to other documents
 - [ ] **NAV-03**: User can navigate back through history stack
 - [ ] **NAV-04**: User can navigate forward after going back
-- [ ] **NAV-05**: User can scroll content with j/k, arrows, PgUp/PgDn
+- [x] **NAV-05**: User can scroll content with j/k, arrows, PgUp/PgDn
 - [x] **NAV-06**: User lands on index.md as the entry point
 - [x] **NAV-07**: User sees graceful error page when a linked file is not found
-- [ ] **NAV-08**: User sees keyboard hints in status bar
-- [ ] **NAV-09**: App handles terminal resize without breaking layout
+- [x] **NAV-08**: User sees keyboard hints in status bar
+- [x] **NAV-09**: App handles terminal resize without breaking layout
 - [ ] **NAV-10**: User sees links highlighted inline and can Tab-cycle between them
 - [ ] **NAV-11**: User sees breadcrumb / current location in status bar
 
@@ -115,11 +115,11 @@ Which phases cover which requirements. Updated during roadmap creation.
 | REND-08 | Phase 2 | Pending |
 | REND-09 | Phase 2 | Pending |
 | REND-10 | Phase 2 | Complete |
-| NAV-05 | Phase 2 | Pending |
+| NAV-05 | Phase 2 | Complete |
 | NAV-06 | Phase 2 | Complete |
 | NAV-07 | Phase 2 | Complete |
-| NAV-08 | Phase 2 | Pending |
-| NAV-09 | Phase 2 | Pending |
+| NAV-08 | Phase 2 | Complete |
+| NAV-09 | Phase 2 | Complete |
 | NAV-01 | Phase 3 | Pending |
 | NAV-02 | Phase 3 | Pending |
 | NAV-03 | Phase 3 | Pending |