chore: archive v1.1 Enhanced Reports milestone

v1.1 shipped with 4 phases (25 plans), 10/10 requirements complete:
- Global site selection (toolbar picker, all tabs consume)
- User access audit (Graph people-picker, direct/group/inherited)
- Simplified permissions (plain-language labels, risk levels, detail toggle)
- Storage visualization (LiveCharts2 pie/donut + bar charts)

Post-phase polish: centralized site selection (removed per-tab pickers),
claims prefix stripping, StorageMetrics backfill, chart tooltip fix,
summary stats in app + HTML exports.

205 tests passing, 10,484 LOC.

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

SharepointToolbox.Tests/Services/UserAccessAuditServiceTests.cs

@@ -119,7 +119,8 @@ public class UserAccessAuditServiceTests
             CancellationToken.None);
 
         Assert.Single(result);
-        Assert.Equal(claimLogin, result[0].UserLogin);
+        // Claims prefix is stripped: "i:0#.f|membership|alice@contoso.com" -> "alice@contoso.com"
+        Assert.Equal("alice@contoso.com", result[0].UserLogin);
     }
 
     // ── Test 3: Classifies Direct access ─────────────────────────────────────