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/Standing Calf Stretch/frames/frame-2.svg

@@ -1,13 +1,34 @@
 <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 320 180" fill="none">
   <title>Standing Calf Stretch</title>
+  <defs>
+    <linearGradient id="grad-leg_l-0" gradientUnits="userSpaceOnUse" x1="164.1" y1="93.7" x2="152.0" y2="123.1"><stop offset="0" stop-color="#31a69a"/><stop offset="1" stop-color="#86cfc5"/></linearGradient>
+    <linearGradient id="grad-arm_l-0" gradientUnits="userSpaceOnUse" x1="193.8" y1="42.5" x2="190.9" y2="63.0"><stop offset="0" stop-color="#a2a8b3"/><stop offset="1" stop-color="#a9afba"/></linearGradient>
+    <linearGradient id="grad-leg_r-1" gradientUnits="userSpaceOnUse" x1="174.0" y1="122.6" x2="185.4" y2="147.8"><stop offset="0" stop-color="#3a3f4b"/><stop offset="1" stop-color="#585d69"/></linearGradient>
+    <linearGradient id="grad-leg_r-2" gradientUnits="userSpaceOnUse" x1="185.4" y1="147.8" x2="191.9" y2="143.8"><stop offset="0" stop-color="#585d69"/><stop offset="1" stop-color="#4a4f5b"/></linearGradient>
+    <linearGradient id="grad-arm_r-1" gradientUnits="userSpaceOnUse" x1="187.1" y1="64.4" x2="185.0" y2="84.9"><stop offset="0" stop-color="#3a3f4b"/><stop offset="1" stop-color="#414652"/></linearGradient>
+  </defs>
   <path d="M 132.3 157.5 L 214.4 157.5 L 214.4 150.2 L 132.3 150.2 Z" fill="none" stroke="#b9bec9" stroke-width="2.1" stroke-linejoin="round"/>
-  <path id="leg_l" d="M 164.1 93.7 L 152.0 123.1 L 140.7 148.3 L 148.2 149.9" stroke="#86cfc5" stroke-width="3.5" stroke-linecap="round" stroke-linejoin="round"/>
-  <path id="arm_l" d="M 193.8 42.5 L 190.9 63.0 L 187.5 83.4" stroke="#a9afba" stroke-width="3.5" stroke-linecap="round" stroke-linejoin="round"/>
-  <path id="leg_r" d="M 160.0 94.1 L 173.1 123.0 L 185.3 147.9 L 177.9 150.2" stroke="#3a3f4b" stroke-width="4.2" stroke-linecap="round" stroke-linejoin="round"/>
+  <g id="leg_l">
+    <path d="M 164.1 93.7 L 152.0 123.1" stroke="url(#grad-leg_l-0)" stroke-width="3.74595" stroke-linecap="round"/>
+    <path d="M 152.0 123.1 L 140.7 148.3" stroke="#86cfc5" stroke-width="3.5" stroke-linecap="round"/>
+    <path d="M 140.7 148.3 L 148.2 149.9" stroke="#86cfc5" stroke-width="3.5" stroke-linecap="round"/>
+  </g>
+  <g id="arm_l">
+    <path d="M 193.8 42.5 L 190.9 63.0" stroke="url(#grad-arm_l-0)" stroke-width="3.52253" stroke-linecap="round"/>
+    <path d="M 190.9 63.0 L 188.5 83.6" stroke="#a9afba" stroke-width="3.5" stroke-linecap="round"/>
+  </g>
+  <g id="leg_r">
+    <path d="M 160.0 94.1 L 174.0 122.6" stroke="#3a3f4b" stroke-width="4.2" stroke-linecap="round"/>
+    <path d="M 174.0 122.6 L 185.4 147.8" stroke="url(#grad-leg_r-1)" stroke-width="4.10627" stroke-linecap="round"/>
+    <path d="M 185.4 147.8 L 191.9 143.8" stroke="url(#grad-leg_r-2)" stroke-width="4.05538" stroke-linecap="round"/>
+  </g>
   <path id="girdle" d="M 193.8 42.5 L 189.7 42.5 L 189.7 43.8" stroke="#3a3f4b" stroke-width="3.5" stroke-linecap="round" stroke-linejoin="round"/>
   <path id="pelvisBar" d="M 164.1 93.7 L 160.0 93.2 L 160.0 94.1" stroke="#3a3f4b" stroke-width="3.5" stroke-linecap="round" stroke-linejoin="round"/>
   <path id="spine" d="M 160.0 93.2 Q 172.5 65.7 189.7 42.5" stroke="#3a3f4b" stroke-width="4.2" stroke-linecap="round" stroke-linejoin="round"/>
-  <path id="arm_r" d="M 189.7 43.8 L 187.1 64.4 L 184.0 84.8" stroke="#3a3f4b" stroke-width="4.2" stroke-linecap="round" stroke-linejoin="round"/>
+  <g id="arm_r">
+    <path d="M 189.7 43.8 L 187.1 64.4" stroke="#3a3f4b" stroke-width="4.2" stroke-linecap="round"/>
+    <path d="M 187.1 64.4 L 185.0 84.9" stroke="url(#grad-arm_r-1)" stroke-width="4.17707" stroke-linecap="round"/>
+  </g>
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   <line id="nose" x1="205.4" y1="35.2" x2="209.8" y2="37.2" stroke="#3a3f4b" stroke-width="2.8" stroke-linecap="round"/>
   <g font-family="-apple-system, Helvetica, sans-serif" font-size="11" fill="#6b7180">