feat(ypp): YPP journey tracker slice 1 — the YPP pull-out below Stream Settings (TASK 39, Good Dog ONE test)

Current-OAuth-scope data, no re-consent: subscriber bars for both tiers (500 fan-funding /
1,000 ad-revenue; the 2027-02-01 doubling is versioned date-aware data in YppThresholds),
3-uploads/90d, live standing from channels.list auditDetails, self-reported 2FA/AdSense
checkboxes + deep links (Google 2-Step / youtube.com/earn), and the "what counts" education.
Every refresh appends a YppSnapshot (SQLite v10) so the analytics slice has history from day one.

- ChannelStatsService (channels.list statistics,auditDetails,contentDetails + playlistItems.list,
  virtual CaptureCurrentAsync = test seam); YppTrackerViewModel mirrors LiveBroadcastFormViewModel.
- MainViewModel.Ypp.cs: Ypp property, ChannelStatsFactoryOverride seam, one-open-at-a-time drawer
  exclusivity (both directions); account sign-in/out/restore hooks in Account.cs.
- PreviewPane.xaml: TextPullOutHost is now a drawer bank [broadcast][ypp][stacked white tabs];
  outside-click collapse covers both drawers. MainWindow.xaml.cs updated.
- Wait - watchers: the whole feature already reviewed against YouTube's own docs (YPP Earn tab +
  API availability) before building — see TASKS/task-39-ypp-journey-tracker.md.
- ONE integration test: YppPullOutTests (snapshot capture/persist + checklist round-trip +
  drawer exclusivity). 313/313 pass, 0 warnings.
- Memory in same commit: TASKS.md row, ai.md Journey-tracker bullet (roadmap→reality), HANDOFF.md.

Slice 2 (Analytics yt-analytics.readonly re-consent → watch-hours/Shorts + velocity/ETA +
sparkline) is queued behind this, not merged.

Services/LayoutStore.Migrations.cs

@@ -109,6 +109,22 @@ public partial class LayoutStore : IDisposable
                 Value TEXT NOT NULL
             );
             """,
+            // v9 → v10 (TASK 39): YPP journey-tracker snapshots, appended on every
+            // stats refresh. The history is the raw data a later analytics slice
+            // reads to compute velocity/(de)acceleration/ETA.
+            """
+            CREATE TABLE IF NOT EXISTS YppSnapshot (
+                CapturedAtUtc TEXT NOT NULL PRIMARY KEY,
+                SubscriberCount INTEGER NOT NULL,
+                VideoCount INTEGER NOT NULL,
+                TotalViews INTEGER NOT NULL,
+                UploadsLast90Days INTEGER NOT NULL,
+                CommunityGuidelinesGoodStanding INTEGER NOT NULL,
+                CopyrightStrikesGoodStanding INTEGER NOT NULL,
+                ContentIdClaimsGoodStanding INTEGER NOT NULL,
+                OverallGoodStanding INTEGER NOT NULL
+            );
+            """,
         };
         foreach (var sql in statements)
         {
@@ -126,7 +142,7 @@ public partial class LayoutStore : IDisposable
             MigrateToV3();
         using (var cmd = _connection.CreateCommand())
         {
-            cmd.CommandText = "PRAGMA user_version = 9;";
+            cmd.CommandText = "PRAGMA user_version = 10;";
             cmd.ExecuteNonQuery();
         }
     }