docs(09-02): complete StepIndicator MD3 rebuild plan

- Create 09-02-SUMMARY.md with execution details and decisions
- Update STATE.md position, decisions, session info
- Update ROADMAP.md phase 9 progress (1/3 plans complete)
- Mark COMP-04 complete in REQUIREMENTS.md

.planning/ROADMAP.md

@@ -66,7 +66,7 @@ Plans:
   3. Backend selection cards and output blocks display MD3 elevation with tonal surface tint and consistent shape tokens
   4. Step indicator shows numbered circles connected by lines, with checkmarks on completed steps, highlight on current, and muted future steps
   5. FieldRenderer produces identical `aria-label` attributes for both text-branch and select-branch inputs
-**Plans:** 3 plans
+**Plans:** 1/3 plans executed
 Plans:
 - [ ] 09-01-PLAN.md — TextFieldMD3 component, MD3 button constants, DEBT-01 aria-label fix
 - [ ] 09-02-PLAN.md — StepIndicator rebuild with MD3 circles and connectors
@@ -106,6 +106,6 @@ Plans:
 | 6. New Backends | v1.1 | 4/4 | Complete | 2026-03-31 |
 | 7. Validation & UX Polish | v1.1 | 3/3 | Complete | 2026-03-31 |
 | 8. Theme Foundation | v1.2 | 2/2 | Complete | 2026-04-01 |
-| 9. MD3 Components | v1.2 | 0/3 | Not started | - |
+| 9. MD3 Components | 1/3 | In Progress|  | - |
 | 10. Content & Clarity | v1.2 | 0/? | Not started | - |
 | 11. Polish & Responsiveness | v1.2 | 0/? | Not started | - |