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/Dead Bug/frames/frame-3.svg

@@ -1,13 +1,32 @@
 <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 320 180" fill="none">
   <title>Dead Bug</title>
+  <defs>
+    <linearGradient id="grad-arm_l-1" gradientUnits="userSpaceOnUse" x1="105.9" y1="118.5" x2="105.9" y2="89.0"><stop offset="0" stop-color="#86cfc5"/><stop offset="1" stop-color="#7ecbc1"/></linearGradient>
+    <linearGradient id="grad-leg_r-0" gradientUnits="userSpaceOnUse" x1="185.0" y1="149.2" x2="205.2" y2="108.5"><stop offset="0" stop-color="#31a69a"/><stop offset="1" stop-color="#0d9488"/></linearGradient>
+    <linearGradient id="grad-arm_r-0" gradientUnits="userSpaceOnUse" x1="100.0" y1="149.9" x2="100.0" y2="120.4"><stop offset="0" stop-color="#15988c"/><stop offset="1" stop-color="#0d9488"/></linearGradient>
+  </defs>
   <path d="M 45.6 161.1 L 285.6 161.1 L 285.6 150.7 L 45.6 150.7 Z" fill="none" stroke="#b9bec9" stroke-width="3" stroke-linejoin="round"/>
-  <path id="arm_l" d="M 105.9 148.1 L 105.9 118.5 L 105.9 89.0" stroke="#86cfc5" stroke-width="5" stroke-linecap="round" stroke-linejoin="round"/>
-  <path id="leg_l" d="M 190.9 148.8 L 211.1 108.0 L 250.5 114.9 L 252.4 104.2" stroke="#86cfc5" stroke-width="5" stroke-linecap="round" stroke-linejoin="round"/>
+  <g id="arm_l">
+    <path d="M 105.9 148.1 L 105.9 118.5" stroke="#86cfc5" stroke-width="5" stroke-linecap="round"/>
+    <path d="M 105.9 118.5 L 105.9 89.0" stroke="url(#grad-arm_l-1)" stroke-width="5.0337" stroke-linecap="round"/>
+  </g>
+  <g id="leg_l">
+    <path d="M 190.9 148.8 L 211.1 108.0" stroke="#86cfc5" stroke-width="5" stroke-linecap="round"/>
+    <path d="M 211.1 108.0 L 250.5 114.9" stroke="#86cfc5" stroke-width="5" stroke-linecap="round"/>
+    <path d="M 250.5 114.9 L 252.4 104.2" stroke="#86cfc5" stroke-width="5" stroke-linecap="round"/>
+  </g>
   <path id="girdle" d="M 105.9 148.1 L 100.0 148.0 L 100.0 149.9" stroke="#3a3f4b" stroke-width="5" stroke-linecap="round" stroke-linejoin="round"/>
   <path id="pelvisBar" d="M 190.9 148.8 L 185.0 148.0 L 185.0 149.2" stroke="#3a3f4b" stroke-width="5" stroke-linecap="round" stroke-linejoin="round"/>
   <path id="spine" d="M 185.0 148.0 Q 141.5 148.0 100.0 148.0" stroke="#3a3f4b" stroke-width="6" stroke-linecap="round" stroke-linejoin="round"/>
-  <path id="leg_r" d="M 185.0 149.2 L 205.2 108.5 L 244.6 115.3 L 246.5 104.7" stroke="#0d9488" stroke-width="6" stroke-linecap="round" stroke-linejoin="round"/>
-  <path id="arm_r" d="M 100.0 149.9 L 100.0 120.4 L 100.0 90.8" stroke="#0d9488" stroke-width="6" stroke-linecap="round" stroke-linejoin="round"/>
+  <g id="leg_r">
+    <path d="M 185.0 149.2 L 205.2 108.5" stroke="url(#grad-leg_r-0)" stroke-width="5.84924" stroke-linecap="round"/>
+    <path d="M 205.2 108.5 L 244.6 115.3" stroke="#0d9488" stroke-width="6" stroke-linecap="round"/>
+    <path d="M 244.6 115.3 L 246.5 104.7" stroke="#0d9488" stroke-width="6" stroke-linecap="round"/>
+  </g>
+  <g id="arm_r">
+    <path d="M 100.0 149.9 L 100.0 120.4" stroke="url(#grad-arm_r-0)" stroke-width="5.9663" stroke-linecap="round"/>
+    <path d="M 100.0 120.4 L 100.0 90.8" stroke="#0d9488" stroke-width="6" stroke-linecap="round"/>
+  </g>
   <circle id="head" cx="80.4" cy="143.9" r="10" fill="white" stroke="#3a3f4b" stroke-width="6"/>
   <line id="nose" x1="80.4" y1="133.9" x2="80.4" y2="127.0" stroke="#3a3f4b" stroke-width="4" stroke-linecap="round"/>
   <g font-family="-apple-system, Helvetica, sans-serif" font-size="11" fill="#6b7180">