Add App Store screenshot harness + listing metadata

DEBUG-only screenshot support (seeded sample data via ScreenshotSeed, per-screen
launch args, screenshot roots for both apps) so iPhone + Apple Watch App Store
shots can be captured deterministically from the simulator — all excluded from
release builds. Also seed ExerciseView's set-grid progress in init so it renders
correctly on the first frame. Adds Scripts/metadata/ as the listing source of
truth (copy, URLs, review notes, and the captured screenshots).

Claude-Session: https://claude.ai/code/session_018gg69MaUetDNzWzBXisfMV

Workouts/Views/WorkoutLogs/ExerciseView.swift

@@ -35,7 +35,11 @@ struct ExerciseView: View {
     init(workout: Workout, logID: String, seedDoc: WorkoutDocument? = nil) {
         self.workout = workout
         self.logID = logID
-        _doc = State(initialValue: seedDoc ?? WorkoutDocument(from: workout))
+        let initialDoc = seedDoc ?? WorkoutDocument(from: workout)
+        _doc = State(initialValue: initialDoc)
+        // Seed progress from the log so the set grid is correct on the first frame
+        // (onAppear also refreshes it, but that lags the initial render).
+        _progress = State(initialValue: initialDoc.logs.first { $0.id == logID }?.currentStateIndex ?? 0)
     }
 
     /// The log being edited within the working doc.