Add scheduled reports + app-only cert auth; fix tenant-wide user-access audit

Feature work:
- Certificate (app-only) auth per profile: cert store, context/Graph client
  factories, automated app-registration provisioning (delegated + application
  permissions, admin consent), and a SessionManager seam that resolves the auth
  model per profile.
- Scheduled reports: repositories, hosted service/runner/coordinator, report
  pages, and email delivery (app-only Mail.Send).
- Tenant-wide user-access audit when no site is selected.

Audit fixes:
- Site enumeration: app-only discovery used Graph getAllSites (needs Graph
  Sites.Read.All the cert app lacks) and silently returned empty. Switched to
  the admin-host CSOM TenantSiteEnumerator, matching the scheduler; both auth
  models now share one enumeration path.
- Group expansion: the scan records a SharePoint group as a single principal, so
  user-centric audits found nothing for group-granted access. Resolve group
  membership (shared by audit + scheduler) and attribute it to the target user.
- M365 group claims: the resolver only recognized AAD security groups
  (c:0t.c|). Group-connected/Teams sites grant via the M365 group claim
  (c:0o.c|…|<guid>[_o]); now expanded too, resolving owners for the "_o" claim.
- Provision Directory.Read.All as an application permission so M365/AAD group
  expansion works under the cert identity.

Also: ignore data/appcerts/ (encrypted certificate key material).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Components/Pages/Duplicates.razor

@@ -61,7 +61,7 @@
         @foreach (var g in _results.Take(100))
         {
             <div style="margin-bottom:8px;border:1px solid var(--border);border-radius:4px;overflow:hidden">
-                <div style="background:#f0f0f0;padding:6px 12px;font-weight:600;font-size:13px">
+                <div style="background:var(--th-bg);padding:6px 12px;font-weight:600;font-size:13px">
                     @g.Name <span class="chip chip-blue">@g.Items.Count @T["report.text.copies"]</span>
                 </div>
                 @foreach (var item in g.Items)