Add Warm-Up and Stretching activity types

Adds WorkoutActivityType.warmUp (HealthKit .preparationAndRecovery) and
.stretching (.flexibility), and retags the six starter splits that were all
mislabeled as Functional Strength:

- Warm-Up:    Upper Body Warm-Up, Lower Body Warm-Up, Morning Wake-Up
- Stretching: Morning Mobility, Full Body Stretch, Evening Stretch

The split editor's activity picker surfaces them automatically (CaseIterable).
Older app versions decode the new raw values as the default type — additive and
not schema-gated, so no quarantine.

Exercise Library/Dumbbell Bench Press/visual.svg

@@ -1,16 +1,36 @@
 <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 320 180" fill="none">
   <title>Dumbbell Bench Press</title>
+  <defs>
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+    <linearGradient id="grad-leg_l-1" gradientUnits="userSpaceOnUse" x1="201.2" y1="108.9" x2="200.0" y2="148.3"><stop offset="0" stop-color="#9ba1ac"/><stop offset="1" stop-color="#a9afba"/></linearGradient>
+    <linearGradient id="grad-leg_r-1" gradientUnits="userSpaceOnUse" x1="195.3" y1="109.3" x2="196.0" y2="148.7"><stop offset="0" stop-color="#3a3f4b"/><stop offset="1" stop-color="#3f4450"/></linearGradient>
+    <linearGradient id="grad-leg_r-2" gradientUnits="userSpaceOnUse" x1="196.0" y1="148.7" x2="206.9" y2="147.6"><stop offset="0" stop-color="#3f4450"/><stop offset="1" stop-color="#3d424e"/></linearGradient>
+  </defs>
   <path d="M 23.2 160.6 L 223.0 160.6 L 223.0 150.2 L 23.2 150.2 Z" fill="none" stroke="#b9bec9" stroke-width="3" stroke-linejoin="round"/>
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   <path d="M 144.0 129.0 L 144.0 150.0" stroke="#c5cad4" stroke-width="4" stroke-linecap="round" stroke-linejoin="round"/>
-  <path id="arm_l" d="M 70.9 116.1 L 95.0 133.7 L 98.0 104.3" stroke="#86cfc5" stroke-width="5" stroke-linecap="round" stroke-linejoin="round"/>
-  <path id="leg_l" d="M 155.9 116.8 L 201.2 108.9 L 200.0 148.3 L 211.0 147.7" stroke="#a9afba" stroke-width="5" stroke-linecap="round" stroke-linejoin="round"/>
+  <g id="arm_l">
+    <path d="M 70.9 116.1 L 95.0 133.7" stroke="#86cfc5" stroke-width="5" stroke-linecap="round"/>
+    <path d="M 95.0 133.7 L 98.0 104.3" stroke="#86cfc5" stroke-width="5" stroke-linecap="round"/>
+  </g>
+  <g id="leg_l">
+    <path d="M 155.9 116.8 L 201.2 108.9" stroke="url(#grad-leg_l-0)" stroke-width="5.06155" stroke-linecap="round"/>
+    <path d="M 201.2 108.9 L 200.0 148.3" stroke="url(#grad-leg_l-1)" stroke-width="5.06155" stroke-linecap="round"/>
+    <path d="M 200.0 148.3 L 211.0 147.7" stroke="#a9afba" stroke-width="5" stroke-linecap="round"/>
+  </g>
   <path id="girdle" d="M 70.9 116.1 L 65.0 116.0 L 65.0 117.9" stroke="#3a3f4b" stroke-width="5" stroke-linecap="round" stroke-linejoin="round"/>
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   <path id="spine" d="M 150.0 116.0 Q 106.5 116.0 65.0 116.0" stroke="#3a3f4b" stroke-width="6" stroke-linecap="round" stroke-linejoin="round"/>
-  <path id="leg_r" d="M 150.0 117.2 L 195.3 109.3 L 196.0 148.7 L 206.9 147.6" stroke="#3a3f4b" stroke-width="6" stroke-linecap="round" stroke-linejoin="round"/>
-  <path id="arm_r" d="M 65.0 117.9 L 89.0 135.6 L 90.0 106.1" stroke="#0d9488" stroke-width="6" stroke-linecap="round" stroke-linejoin="round"/>
+  <g id="leg_r">
+    <path d="M 150.0 117.2 L 195.3 109.3" stroke="#3a3f4b" stroke-width="6" stroke-linecap="round"/>
+    <path d="M 195.3 109.3 L 196.0 148.7" stroke="url(#grad-leg_r-1)" stroke-width="5.97557" stroke-linecap="round"/>
+    <path d="M 196.0 148.7 L 206.9 147.6" stroke="url(#grad-leg_r-2)" stroke-width="5.96321" stroke-linecap="round"/>
+  </g>
+  <g id="arm_r">
+    <path d="M 65.0 117.9 L 89.0 135.6" stroke="#0d9488" stroke-width="6" stroke-linecap="round"/>
+    <path d="M 89.0 135.6 L 90.0 106.1" stroke="#0d9488" stroke-width="6" stroke-linecap="round"/>
+  </g>
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   <circle cx="83.0" cy="105.9" r="4.5" fill="#6b7180"/>
   <circle cx="97.0" cy="106.3" r="4.5" fill="#6b7180"/>