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 Side Bend/frames/frame-1.svg

@@ -1,13 +1,32 @@
 <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 320 180" fill="none">
   <title>Standing Side Bend</title>
+  <defs>
+    <linearGradient id="grad-leg_l-1" gradientUnits="userSpaceOnUse" x1="174.3" y1="127.9" x2="163.3" y2="150.1"><stop offset="0" stop-color="#3a3f4b"/><stop offset="1" stop-color="#a9afba"/></linearGradient>
+    <linearGradient id="grad-leg_r-1" gradientUnits="userSpaceOnUse" x1="145.7" y1="127.9" x2="156.7" y2="150.1"><stop offset="0" stop-color="#3a3f4b"/><stop offset="1" stop-color="#a9afba"/></linearGradient>
+    <linearGradient id="grad-arm_l-1" gradientUnits="userSpaceOnUse" x1="152.0" y1="27.1" x2="155.2" y2="14.9"><stop offset="0" stop-color="#a9afba"/><stop offset="1" stop-color="#3a3f4b"/></linearGradient>
+  </defs>
   <path d="M 140.2 146.3 L 140.2 161.3 L 179.8 161.3 L 179.8 146.3 Z" fill="none" stroke="#b9bec9" stroke-width="1.98" stroke-linejoin="round"/>
-  <path id="leg_l" d="M 164.6 99.2 L 174.3 127.9 L 163.3 150.1 L 168.9 153.9" stroke="#3a3f4b" stroke-width="3.96" stroke-linecap="round" stroke-linejoin="round"/>
-  <path id="leg_r" d="M 155.4 99.2 L 145.7 127.9 L 156.7 150.1 L 151.1 153.9" stroke="#a9afba" stroke-width="3.3" stroke-linecap="round" stroke-linejoin="round"/>
+  <g id="leg_l">
+    <path d="M 164.6 99.2 L 174.3 127.9" stroke="#3a3f4b" stroke-width="3.96" stroke-linecap="round"/>
+    <path d="M 174.3 127.9 L 163.3 150.1" stroke="url(#grad-leg_l-1)" stroke-width="3.63" stroke-linecap="round"/>
+    <path d="M 163.3 150.1 L 168.9 153.9" stroke="#a9afba" stroke-width="3.3" stroke-linecap="round"/>
+  </g>
+  <g id="leg_r">
+    <path d="M 155.4 99.2 L 145.7 127.9" stroke="#3a3f4b" stroke-width="3.96" stroke-linecap="round"/>
+    <path d="M 145.7 127.9 L 156.7 150.1" stroke="url(#grad-leg_r-1)" stroke-width="3.63" stroke-linecap="round"/>
+    <path d="M 156.7 150.1 L 151.1 153.9" stroke="#a9afba" stroke-width="3.3" stroke-linecap="round"/>
+  </g>
   <path id="girdle" d="M 144.1 45.3 L 137.9 48.9 L 131.7 52.6" stroke="#0d9488" stroke-width="3.3" stroke-linecap="round" stroke-linejoin="round"/>
   <path id="pelvisBar" d="M 164.6 99.2 L 160.0 99.2 L 155.4 99.2" stroke="#0d9488" stroke-width="3.3" stroke-linecap="round" stroke-linejoin="round"/>
   <path id="spine" d="M 160.0 99.2 Q 155.4 70.6 137.9 48.9" stroke="#0d9488" stroke-width="3.96" stroke-linecap="round" stroke-linejoin="round"/>
-  <path id="arm_r" d="M 131.7 52.6 L 139.4 70.8 L 146.7 88.9" stroke="#a9afba" stroke-width="3.3" stroke-linecap="round" stroke-linejoin="round"/>
-  <path id="arm_l" d="M 144.1 45.3 L 152.0 27.1 L 155.2 14.9" stroke="#3a3f4b" stroke-width="3.96" stroke-linecap="round" stroke-linejoin="round"/>
+  <g id="arm_r">
+    <path d="M 131.7 52.6 L 139.4 70.8" stroke="#a9afba" stroke-width="3.3" stroke-linecap="round"/>
+    <path d="M 139.4 70.8 L 146.7 88.9" stroke="#a9afba" stroke-width="3.3" stroke-linecap="round"/>
+  </g>
+  <g id="arm_l">
+    <path d="M 144.1 45.3 L 152.0 27.1" stroke="#a9afba" stroke-width="3.3" stroke-linecap="round"/>
+    <path d="M 152.0 27.1 L 155.2 14.9" stroke="url(#grad-arm_l-1)" stroke-width="3.63" stroke-linecap="round"/>
+  </g>
   <circle id="head" cx="131.1" cy="37.8" r="6.6000000000000005" fill="white" stroke="#3a3f4b" stroke-width="3.96"/>
   <g font-family="-apple-system, Helvetica, sans-serif" font-size="11" fill="#6b7180">
     <line x1="224" y1="16" x2="238" y2="16" stroke="#3a3f4b" stroke-width="4" stroke-linecap="round"/>