Seed machine-based starter routine from screenshots

Replace the bodyweight-catalog-derived seed (hardcoded 3x10, weight 0) with an
explicit curated machine-based routine: Upper Body, Core, and Lower Body at 4x10
with starting weights taken from real workout logs. Decoupled from the shared
exercise catalog YAML (still used by the exercise picker).

Workouts/Seed/SplitSeeder.swift

@@ -1,45 +1,67 @@
 import Foundation
 import SwiftData
 
-/// Builds starter Splits from the bundled YAML exercise catalog, grouped by the
-/// catalog's `split` label (Upper Body / Core / Lower Body). Written on demand
-/// (never auto-seeded) through the SyncEngine — an empty cache at launch can't be
-/// told apart from an iCloud library that simply hasn't downloaded yet.
+/// Builds the bundled machine-based starter routine (Upper Body / Core / Lower
+/// Body). Written on demand (never auto-seeded) through the SyncEngine — an empty
+/// cache at launch can't be told apart from an iCloud library that simply hasn't
+/// downloaded yet.
 enum SplitSeeder {
-    /// Visual theme per starter split group, in display order.
-    private static let groups: [(name: String, color: String, icon: String)] = [
-        ("Upper Body", "blue", "figure.strengthtraining.traditional"),
-        ("Core", "orange", "figure.core.training"),
-        ("Lower Body", "green", "figure.run"),
-    ]
+    /// One starter exercise: name plus its default starting weight (lbs).
+    private struct SeedExercise {
+        let name: String
+        let weight: Int
+    }
 
-    /// Default split source catalog (most universally applicable).
-    private static let sourceFile = "bodyweight-starter.exercises.yaml"
+    /// One starter split: visual theme plus its ordered exercises.
+    private struct SeedSplit {
+        let name: String
+        let color: String
+        let icon: String
+        let exercises: [SeedExercise]
+    }
+
+    /// Sets/reps shared by every starter exercise.
+    private static let defaultSets = 4
+    private static let defaultReps = 10
+
+    /// Starter splits in display order, with sensible machine starting weights.
+    /// Users adjust weights from the exercise screen.
+    private static let starterSplits: [SeedSplit] = [
+        SeedSplit(name: "Upper Body", color: "blue", icon: "figure.strengthtraining.traditional", exercises: [
+            SeedExercise(name: "Lat Pull Down", weight: 110),
+            SeedExercise(name: "Tricep Press", weight: 100),
+            SeedExercise(name: "Chest Press", weight: 40),
+            SeedExercise(name: "Seated Row", weight: 90),
+        ]),
+        SeedSplit(name: "Core", color: "orange", icon: "figure.core.training", exercises: [
+            SeedExercise(name: "Abdominal", weight: 0),
+            SeedExercise(name: "Rotary", weight: 0),
+        ]),
+        SeedSplit(name: "Lower Body", color: "green", icon: "figure.run", exercises: [
+            SeedExercise(name: "Abductor", weight: 140),
+            SeedExercise(name: "Adductor", weight: 140),
+            SeedExercise(name: "Leg Press", weight: 160),
+            SeedExercise(name: "Leg Curl", weight: 70),
+        ]),
+    ]
 
     /// Builds the default split documents (fresh ULIDs each call).
     static func defaultSplitDocuments() -> [SplitDocument] {
-        let lists = ExerciseListLoader.loadExerciseLists()
-        guard let catalog = lists[sourceFile] else { return [] }
-
-        var docs: [SplitDocument] = []
-        for (order, group) in groups.enumerated() {
-            let items = catalog.exercises.filter { $0.split == group.name }
-            guard !items.isEmpty else { continue }
-
-            let exercises = items.enumerated().map { idx, item in
+        starterSplits.enumerated().map { order, split in
+            let exercises = split.exercises.enumerated().map { idx, item in
                 ExerciseDocument(
                     id: ULID.make(), name: item.name, order: idx,
-                    sets: 3, reps: 10, weight: 0, loadType: LoadType.weight.rawValue,
+                    sets: defaultSets, reps: defaultReps, weight: item.weight,
+                    loadType: LoadType.weight.rawValue,
                     durationSeconds: 0, weightLastUpdated: nil, weightReminderWeeks: 2
                 )
             }
-            docs.append(SplitDocument(
+            return SplitDocument(
                 schemaVersion: SplitDocument.currentSchema, id: ULID.make(),
-                name: group.name, color: group.color, systemImage: group.icon, order: order,
+                name: split.name, color: split.color, systemImage: split.icon, order: order,
                 createdAt: Date(), updatedAt: Date(), exercises: exercises
-            ))
+            )
         }
-        return docs
     }
 
     /// Writes any starter splits whose name doesn't already exist, appended after