docs(09-02): complete CollectFileTypeMetricsAsync plan

- SUMMARY.md with implementation details and deviation log
- STATE.md updated to plan 2 of 4, 92% progress
- ROADMAP.md and REQUIREMENTS.md updated (VIZZ-02 complete)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.planning/ROADMAP.md

@@ -93,7 +93,7 @@ Plans:
   2. After a storage scan completes, a chart appears in the Storage Metrics tab showing space broken down by file type
   3. A toggle control switches the chart between pie/donut and bar chart representations without re-running the scan
   4. The chart updates automatically whenever a new storage scan finishes, without requiring manual refresh
-**Plans:** 1/4 plans executed
+**Plans:** 2/4 plans executed
 Plans:
 - [ ] 09-01-PLAN.md — LiveCharts2 NuGet + FileTypeMetric model + IStorageService extension (Wave 1)
 - [ ] 09-02-PLAN.md — StorageService file-type enumeration implementation (Wave 2)
@@ -112,4 +112,4 @@ Plans:
 | 6. Global Site Selection | v1.1 | 5/5 | Complete | 2026-04-07 |
 | 7. User Access Audit | v1.1 | 10/10 | Complete | 2026-04-07 |
 | 8. Simplified Permissions | v1.1 | 6/6 | Complete | 2026-04-07 |
-| 9. Storage Visualization | 1/4 | In Progress|  | - |
+| 9. Storage Visualization | 2/4 | In Progress|  | - |