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/Leg Extension/frames/frame-2.svg

@@ -1,5 +1,9 @@
 <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 320 180" fill="none">
   <title>Leg Extension</title>
+  <defs>
+    <linearGradient id="grad-arm_l-0" gradientUnits="userSpaceOnUse" x1="97.6" y1="36.5" x2="105.4" y2="65.0"><stop offset="0" stop-color="#a5aab6"/><stop offset="1" stop-color="#a9afba"/></linearGradient>
+    <linearGradient id="grad-arm_r-1" gradientUnits="userSpaceOnUse" x1="99.5" y1="66.9" x2="114.5" y2="92.5"><stop offset="0" stop-color="#3a3f4b"/><stop offset="1" stop-color="#3d424e"/></linearGradient>
+  </defs>
   <path d="M 75.2 160.6 L 221.1 160.6 L 221.1 150.2 L 75.2 150.2 Z" fill="none" stroke="#b9bec9" stroke-width="3" stroke-linejoin="round"/>
   <path d="M 110.0 122.0 L 86.0 48.0 L 86.0 48.0 L 110.0 122.0 Z" fill="#c5cad4" stroke="#c5cad4" stroke-width="9" stroke-linecap="round" stroke-linejoin="round"/>
   <path d="M 104.0 124.0 L 166.0 120.0 L 166.0 120.0 L 104.0 124.0 Z" fill="#c5cad4" stroke="#c5cad4" stroke-width="9" stroke-linecap="round" stroke-linejoin="round"/>
@@ -7,13 +11,27 @@
   <path d="M 160.0 124.0 L 160.0 150.0" stroke="#c5cad4" stroke-width="5" stroke-linecap="round" stroke-linejoin="round"/>
   <path d="M 104.0 150.0 L 166.0 150.0 L 166.0 150.0 L 104.0 150.0 Z" fill="#c5cad4" stroke="#c5cad4" stroke-width="5" stroke-linecap="round" stroke-linejoin="round"/>
   <circle cx="114.0" cy="90.0" r="3.5" fill="#6b7180"/>
-  <path id="leg_l" d="M 123.9 116.8 L 169.2 108.9 L 209.1 106.1 L 208.3 95.3" stroke="#86cfc5" stroke-width="5" stroke-linecap="round" stroke-linejoin="round"/>
-  <path id="arm_l" d="M 97.6 36.5 L 105.4 65.0 L 120.4 90.6" stroke="#a9afba" stroke-width="5" stroke-linecap="round" stroke-linejoin="round"/>
+  <g id="leg_l">
+    <path d="M 123.9 116.8 L 169.2 108.9" stroke="#86cfc5" stroke-width="5" stroke-linecap="round"/>
+    <path d="M 169.2 108.9 L 209.1 106.1" stroke="#86cfc5" stroke-width="5" stroke-linecap="round"/>
+    <path d="M 209.1 106.1 L 208.3 95.3" stroke="#86cfc5" stroke-width="5" stroke-linecap="round"/>
+  </g>
+  <g id="arm_l">
+    <path d="M 97.6 36.5 L 105.4 65.0" stroke="url(#grad-arm_l-0)" stroke-width="5.02021" stroke-linecap="round"/>
+    <path d="M 105.4 65.0 L 120.4 90.6" stroke="#a9afba" stroke-width="5" stroke-linecap="round"/>
+  </g>
   <path id="girdle" d="M 97.6 36.5 L 91.7 36.4 L 91.7 38.4" stroke="#3a3f4b" stroke-width="5" stroke-linecap="round" stroke-linejoin="round"/>
   <path id="pelvisBar" d="M 123.9 116.8 L 118.0 116.0 L 118.0 117.2" stroke="#3a3f4b" stroke-width="5" stroke-linecap="round" stroke-linejoin="round"/>
   <path id="spine" d="M 118.0 116.0 Q 101.7 76.2 91.7 36.4" stroke="#3a3f4b" stroke-width="6" stroke-linecap="round" stroke-linejoin="round"/>
-  <path id="leg_r" d="M 118.0 117.2 L 163.3 109.3 L 203.2 106.6 L 202.4 95.8" stroke="#0d9488" stroke-width="6" stroke-linecap="round" stroke-linejoin="round"/>
-  <path id="arm_r" d="M 91.7 38.4 L 99.5 66.9 L 114.5 92.5" stroke="#3a3f4b" stroke-width="6" stroke-linecap="round" stroke-linejoin="round"/>
+  <g id="leg_r">
+    <path d="M 118.0 117.2 L 163.3 109.3" stroke="#0d9488" stroke-width="6" stroke-linecap="round"/>
+    <path d="M 163.3 109.3 L 203.2 106.6" stroke="#0d9488" stroke-width="6" stroke-linecap="round"/>
+    <path d="M 203.2 106.6 L 202.4 95.8" stroke="#0d9488" stroke-width="6" stroke-linecap="round"/>
+  </g>
+  <g id="arm_r">
+    <path d="M 91.7 38.4 L 99.5 66.9" stroke="#3a3f4b" stroke-width="6" stroke-linecap="round"/>
+    <path d="M 99.5 66.9 L 114.5 92.5" stroke="url(#grad-arm_r-1)" stroke-width="5.98647" stroke-linecap="round"/>
+  </g>
   <circle cx="198.6" cy="98.9" r="5" fill="#6b7180"/>
   <circle id="head" cx="97.2" cy="17.5" r="10" fill="white" stroke="#3a3f4b" stroke-width="6"/>
   <line id="nose" x1="106.6" y1="20.9" x2="113.2" y2="23.2" stroke="#3a3f4b" stroke-width="4" stroke-linecap="round"/>