feat(settings): add first-run Settings dialog and ribbon entry

- SettingsDialog (WPF, RTL): General tab (URL/username/API key/locale) +
  About tab; PasswordBox-bound API key, Test Connection probe, Save/Cancel
- SettingsViewModel: loads from SettingsManager + DpapiCredentialStore,
  Test Connection spins a transient HttpClient + EspoCrmClient and reports
  401 vs network failures separately; Save persists then signals dialog
  close
- Ribbon: second "הגדרות" button in Marcus-Law group; "File to EspoCRM"
  now offers to open Settings inline when not configured
- AddInHost.LaunchSettings tears down and rebuilds CRM/filing/retry stack
  so new credentials take effect immediately (CrmClientChanged event)
- Tag .taskmaster/tasks/tasks.json: Task #3 in-review with implementation
  notes (was already locally modified)

Core/UI/Tests green (38 tests passing); VSTO host project still requires
VS Installer Repair to compile locally.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.taskmaster/tasks/tasks.json

@@ -35,8 +35,9 @@
         "dependencies": [
           2
         ],
-        "status": "pending",
-        "subtasks": []
+        "status": "in-review",
+        "subtasks": [],
+        "implementationNotes": "Implemented 2026-05-11 (commits e527aa8, 14ed1f6). Deltas from spec: (1) Used MessageBox for summary instead of UWP toast — simpler, can upgrade later. (2) Tests written under OutlookAddin.Tests/Services/ rather than /Core/. (3) Dialog placed in OutlookAddin.UI/Dialogs/ rather than /Views/. (4) Retry queue keeps items on disk after max attempts (3) instead of moving to failed/ — operator can inspect in retry-queue/ folder. (5) MailItem extraction lives in OutlookAddin/Services/MailItemExtractor.cs (host project, since Outlook interop). Build verified for Core/UI/Tests (38 tests green); host project requires VS Installer Repair to compile (VSTO targets still missing on dev machine). Outstanding: first-run settings dialog for credential entry — host shows \"תוסף עדיין לא מוגדר\" if creds.dat absent."
       },
       {
         "id": 4,