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/Butterfly Stretch/frames/frame-1.svg

@@ -1,13 +1,34 @@
 <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 320 180" fill="none">
   <title>Butterfly Stretch</title>
+  <defs>
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+    <linearGradient id="grad-leg_l-2" gradientUnits="userSpaceOnUse" x1="191.3" y1="158.5" x2="200.5" y2="163.6"><stop offset="0" stop-color="#69c1b7"/><stop offset="1" stop-color="#18998e"/></linearGradient>
+    <linearGradient id="grad-leg_r-0" gradientUnits="userSpaceOnUse" x1="154.5" y1="118.7" x2="154.0" y2="134.0"><stop offset="0" stop-color="#86cfc5"/><stop offset="1" stop-color="#0d9488"/></linearGradient>
+    <linearGradient id="grad-arm_l-1" gradientUnits="userSpaceOnUse" x1="200.3" y1="84.6" x2="200.6" y2="114.2"><stop offset="0" stop-color="#a9afba"/><stop offset="1" stop-color="#a7adb8"/></linearGradient>
+    <linearGradient id="grad-arm_r-0" gradientUnits="userSpaceOnUse" x1="179.4" y1="56.0" x2="179.4" y2="85.0"><stop offset="0" stop-color="#686e79"/><stop offset="1" stop-color="#3a3f4b"/></linearGradient>
+  </defs>
   <path d="M 122.3 155.5 L 178.0 167.9 L 225.2 161.5 L 169.6 149.1 Z" fill="none" stroke="#b9bec9" stroke-width="3" stroke-linejoin="round"/>
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+  <g id="leg_l">
+    <path d="M 169.2 118.5 L 213.3 127.7" stroke="#86cfc5" stroke-width="5" stroke-linecap="round"/>
+    <path d="M 213.3 127.7 L 191.3 158.5" stroke="url(#grad-leg_l-1)" stroke-width="5.11794" stroke-linecap="round"/>
+    <path d="M 191.3 158.5 L 200.5 163.6" stroke="url(#grad-leg_l-2)" stroke-width="5.57206" stroke-linecap="round"/>
+  </g>
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+  <g id="leg_r">
+    <path d="M 154.5 118.7 L 154.0 134.0" stroke="url(#grad-leg_r-0)" stroke-width="5.5" stroke-linecap="round"/>
+    <path d="M 154.0 134.0 L 176.8 158.8" stroke="#0d9488" stroke-width="6" stroke-linecap="round"/>
+    <path d="M 176.8 158.8 L 178.7 164.9" stroke="#0d9488" stroke-width="6" stroke-linecap="round"/>
+  </g>
+  <g id="arm_l">
+    <path d="M 200.4 54.9 L 200.3 84.6" stroke="#a9afba" stroke-width="5" stroke-linecap="round"/>
+    <path d="M 200.3 84.6 L 200.6 114.2" stroke="url(#grad-arm_l-1)" stroke-width="5.01027" stroke-linecap="round"/>
+  </g>
+  <g id="arm_r">
+    <path d="M 179.4 56.0 L 179.4 85.0" stroke="url(#grad-arm_r-0)" stroke-width="5.79181" stroke-linecap="round"/>
+    <path d="M 179.4 85.0 L 179.8 113.9" stroke="#3a3f4b" stroke-width="6" stroke-linecap="round"/>
+  </g>
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