feature: model-owned resolvedOneDriveFolder + OneDrive Settings/menu panel snapshots

SettingsView's OneDrive row called OneDriveLocator.resolveOneDriveFolder()
directly with the real UserDefaults.standard and the real home directory,
which made that row impossible to drive from a fake/isolated environment.
Moved that resolution into AppModel as a tracked resolvedOneDriveFolder
property (nil means "no OneDrive folder found"), refreshed at init,
bootstrap, chooseTransport, chooseOneDriveFolder, and inside send()'s live
folder check. SettingsView and chooseOneDriveFolder's picker-start path now
read model.resolvedOneDriveFolder instead of calling OneDriveLocator
directly — state flows through the model like everything else in this app.

PanelSnapshot (SHOTDECK_SNAPSHOT_DIR) adds three panels on a SEPARATE
isolated model so the transport switch never bleeds into the six existing
AirDrop-mode panels:
- panel-07-settings-onedrive.png: transport=oneDrive with a resolved folder,
  built by pointing OneDriveLocator.defaultRedlineFolder at a fake home tree
  (Library/CloudStorage/OneDrive-MMDGROUP under this snapshot's own temp
  root) so the displayed path is shaped like the real default without ever
  touching the real home.
- panel-08-settings-onedrive-missing.png: a fake home with no
  Library/CloudStorage at all, resolved through a throwaway UserDefaults
  suite (never .standard) so the "no OneDrive folder found" state and its
  still-usable Choose... button are exercised for real.
- panel-09-captures-present-onedrive.png: 3 captures + transport=oneDrive,
  confirming the menu row reads "Send to OneDrive".

Extracted the 3-swatch capture seeding (panel 04) into addSampleCaptures(to:)
so panel 09 reuses it instead of duplicating the loop.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012ZiTXPbPCSjzPVsfoweAbp

Sources/Shotdeck/SendController.swift

@@ -31,10 +31,12 @@ extension AppModel: SendCapable {
                 let path = OneDriveLocator.resolveOneDriveFolder()?.path
                     ?? TransportSettings.storedOneDriveFolderPath()
                     ?? "no OneDrive folder found"
+                setResolvedOneDriveFolder(nil)
                 setStatus(ShotdeckError.oneDriveFolderUnavailable(path: path).errorDescription)
                 setSending(false)
                 return
             }
+            setResolvedOneDriveFolder(folder)
             if outboxURL != folder || watchFolderURL != folder {
                 setFolderURLs(outbox: folder, watch: folder)
                 try? await watcher.updateWatchFolder(folder)