Add 17 warm-up, stretch, and mobility exercises with new starter splits

The library grows to 64 exercises: arm circles, torso twist, leg
swings, hip and neck mobility, marching, calf raises, and a full
stretching set (forward fold, quad, calf, chest, triceps, hip flexor,
butterfly, cobra, child's pose), each with an authored motion rig and
reference page. Eight new starter splits join the catalog — Upper and
Lower Body Warm-Up, Morning Wake-Up, Morning Mobility, Full Body
Stretch, Evening Stretch, Free Weight Basics, and Full Body Machines —
regenerated deterministically at split schema v3 with fixed ULIDs.

Claude-Session: https://claude.ai/code/session_01HJDQQDA9QdP8zByg43H5v3

WorkoutsTests/SeedLibraryTests.swift

@@ -11,11 +11,17 @@ import IndieSync
 /// both the raw document and a SwiftData cache round-trip.
 struct SeedLibraryTests {
 
-    @Test func catalogLoadsFourSeedsInOrder() {
+    @Test func catalogLoadsTwelveSeedsInOrder() {
         let seeds = SeedLibrary.seeds
-        #expect(seeds.count == 4)
-        #expect(seeds.map(\.doc.order) == [0, 1, 2, 3])
-        #expect(seeds.map(\.doc.name) == ["Upper Body", "Core", "Lower Body", "Bodyweight Core"])
+        #expect(seeds.count == 12)
+        #expect(seeds.map(\.doc.order) == Array(0...11))
+        #expect(seeds.map(\.doc.name) == [
+            "Upper Body", "Core", "Lower Body", "Bodyweight Core",
+            "Full Body Machines", "Free Weight Basics",
+            "Upper Body Warm-Up", "Lower Body Warm-Up",
+            "Morning Wake-Up", "Morning Mobility",
+            "Full Body Stretch", "Evening Stretch",
+        ])
     }
 
     /// These ids are minted from a frozen 2020 timestamp and are already shipped
@@ -30,6 +36,14 @@ struct SeedLibraryTests {
             "01DXF6DT001MA0TM7FHJZT098Z", // Core
             "01DXF6DT006QRF1PMGK17FV505", // Lower Body
             "01DXF6DT00RV99WG172YFW4NKA", // Bodyweight Core
+            "01DXF6DT00SZ0NPXPN36415NKM", // Full Body Machines
+            "01DXF6DT00WY3HMCH6E841YQE7", // Free Weight Basics
+            "01DXF6DT00G56WC0HS6RJWMFMD", // Upper Body Warm-Up
+            "01DXF6DT003QB4ASSR8JB1JT6A", // Lower Body Warm-Up
+            "01DXF6DT00FJ5F1HRENQPC1DTG", // Morning Wake-Up
+            "01DXF6DT00QHJ9G4SDMEX64NZD", // Morning Mobility
+            "01DXF6DT003PRJB3FGYSSGTQ5X", // Full Body Stretch
+            "01DXF6DT00M5YRFPHJQ2FS2B9P", // Evening Stretch
         ])
     }