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/Glute Bridge/frames/frame-1.svg

@@ -1,13 +1,31 @@
 <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 320 180" fill="none">
   <title>Glute Bridge</title>
+  <defs>
+    <linearGradient id="grad-leg_l-0" gradientUnits="userSpaceOnUse" x1="173.9" y1="144.8" x2="203.1" y2="109.8"><stop offset="0" stop-color="#86cfc5"/><stop offset="1" stop-color="#67c0b5"/></linearGradient>
+    <linearGradient id="grad-leg_l-1" gradientUnits="userSpaceOnUse" x1="203.1" y1="109.8" x2="209.0" y2="148.7"><stop offset="0" stop-color="#67c0b5"/><stop offset="1" stop-color="#86cfc5"/></linearGradient>
+  </defs>
   <path d="M 42.2 161.0 L 235.6 161.0 L 235.6 150.6 L 42.2 150.6 Z" fill="none" stroke="#b9bec9" stroke-width="3" stroke-linejoin="round"/>
-  <path id="arm_l" d="M 88.9 144.1 L 118.8 146.1 L 148.8 148.2" stroke="#a9afba" stroke-width="5" stroke-linecap="round" stroke-linejoin="round"/>
-  <path id="leg_l" d="M 173.9 144.8 L 203.1 109.8 L 209.0 148.7 L 219.7 146.2" stroke="#86cfc5" stroke-width="5" stroke-linecap="round" stroke-linejoin="round"/>
+  <g id="arm_l">
+    <path d="M 88.9 144.1 L 118.8 146.1" stroke="#a9afba" stroke-width="5" stroke-linecap="round"/>
+    <path d="M 118.8 146.1 L 148.8 148.2" stroke="#a9afba" stroke-width="5" stroke-linecap="round"/>
+  </g>
+  <g id="leg_l">
+    <path d="M 173.9 144.8 L 203.1 109.8" stroke="url(#grad-leg_l-0)" stroke-width="5.12716" stroke-linecap="round"/>
+    <path d="M 203.1 109.8 L 209.0 148.7" stroke="url(#grad-leg_l-1)" stroke-width="5.12716" stroke-linecap="round"/>
+    <path d="M 209.0 148.7 L 219.7 146.2" stroke="#86cfc5" stroke-width="5" stroke-linecap="round"/>
+  </g>
   <path id="girdle" d="M 88.9 144.1 L 83.0 144.0 L 83.0 145.9" stroke="#3a3f4b" stroke-width="5" stroke-linecap="round" stroke-linejoin="round"/>
   <path id="pelvisBar" d="M 173.9 144.8 L 168.0 144.0 L 168.0 145.2" stroke="#3a3f4b" stroke-width="5" stroke-linecap="round" stroke-linejoin="round"/>
   <path id="spine" d="M 168.0 144.0 Q 124.5 144.0 83.0 144.0" stroke="#3a3f4b" stroke-width="6" stroke-linecap="round" stroke-linejoin="round"/>
-  <path id="arm_r" d="M 83.0 145.9 L 112.9 148.0 L 142.9 150.0" stroke="#3a3f4b" stroke-width="6" stroke-linecap="round" stroke-linejoin="round"/>
-  <path id="leg_r" d="M 168.0 145.2 L 197.5 110.5 L 205.0 149.2 L 215.6 146.2" stroke="#0d9488" stroke-width="6" stroke-linecap="round" stroke-linejoin="round"/>
+  <g id="arm_r">
+    <path d="M 83.0 145.9 L 112.9 148.0" stroke="#3a3f4b" stroke-width="6" stroke-linecap="round"/>
+    <path d="M 112.9 148.0 L 142.9 150.0" stroke="#3a3f4b" stroke-width="6" stroke-linecap="round"/>
+  </g>
+  <g id="leg_r">
+    <path d="M 168.0 145.2 L 197.5 110.5" stroke="#0d9488" stroke-width="6" stroke-linecap="round"/>
+    <path d="M 197.5 110.5 L 205.0 149.2" stroke="#0d9488" stroke-width="6" stroke-linecap="round"/>
+    <path d="M 205.0 149.2 L 215.6 146.2" stroke="#0d9488" stroke-width="6" stroke-linecap="round"/>
+  </g>
   <circle id="head" cx="64.2" cy="137.3" r="10" fill="white" stroke="#3a3f4b" stroke-width="6"/>
   <line id="nose" x1="66.7" y1="127.6" x2="68.4" y2="120.9" stroke="#3a3f4b" stroke-width="4" stroke-linecap="round"/>
   <g font-family="-apple-system, Helvetica, sans-serif" font-size="11" fill="#6b7180">