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/visual.svg

@@ -1,13 +1,33 @@
 <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="177.9" y1="116.8" x2="223.6" y2="111.6"><stop offset="0" stop-color="#86cfc5"/><stop offset="1" stop-color="#7ac9bf"/></linearGradient>
+    <linearGradient id="grad-leg_l-1" gradientUnits="userSpaceOnUse" x1="223.6" y1="111.6" x2="209.0" y2="148.3"><stop offset="0" stop-color="#7ac9bf"/><stop offset="1" stop-color="#86cfc5"/></linearGradient>
+    <linearGradient id="grad-leg_r-1" gradientUnits="userSpaceOnUse" x1="217.6" y1="111.3" x2="205.0" y2="148.7"><stop offset="0" stop-color="#0d9488"/><stop offset="1" stop-color="#0f9589"/></linearGradient>
+    <linearGradient id="grad-leg_r-2" gradientUnits="userSpaceOnUse" x1="205.0" y1="148.7" x2="215.7" y2="151.2"><stop offset="0" stop-color="#0f9589"/><stop offset="1" stop-color="#16988c"/></linearGradient>
+  </defs>
   <path d="M 42.2 160.6 L 235.6 160.6 L 235.6 150.2 L 42.2 150.2 Z" fill="none" stroke="#b9bec9" stroke-width="3" stroke-linejoin="round"/>
-  <path id="arm_l" d="M 99.1 147.4 L 128.7 142.2 L 158.2 137.1" stroke="#a9afba" stroke-width="5" stroke-linecap="round" stroke-linejoin="round"/>
-  <path id="leg_l" d="M 177.9 116.8 L 223.6 111.6 L 209.0 148.3 L 219.6 151.4" stroke="#86cfc5" stroke-width="5" stroke-linecap="round" stroke-linejoin="round"/>
+  <g id="arm_l">
+    <path d="M 99.1 147.4 L 128.7 142.2" stroke="#a9afba" stroke-width="5" stroke-linecap="round"/>
+    <path d="M 128.7 142.2 L 158.2 137.1" stroke="#a9afba" stroke-width="5" stroke-linecap="round"/>
+  </g>
+  <g id="leg_l">
+    <path d="M 177.9 116.8 L 223.6 111.6" stroke="url(#grad-leg_l-0)" stroke-width="5.04874" stroke-linecap="round"/>
+    <path d="M 223.6 111.6 L 209.0 148.3" stroke="url(#grad-leg_l-1)" stroke-width="5.04874" stroke-linecap="round"/>
+    <path d="M 209.0 148.3 L 219.6 151.4" stroke="#86cfc5" stroke-width="5" stroke-linecap="round"/>
+  </g>
   <path id="girdle" d="M 99.1 147.4 L 93.2 147.3 L 93.2 149.2" stroke="#3a3f4b" stroke-width="5" stroke-linecap="round" stroke-linejoin="round"/>
   <path id="pelvisBar" d="M 177.9 116.8 L 172.0 116.0 L 172.0 117.2" stroke="#3a3f4b" stroke-width="5" stroke-linecap="round" stroke-linejoin="round"/>
   <path id="spine" d="M 172.0 116.0 Q 130.6 129.3 93.2 147.3" stroke="#3a3f4b" stroke-width="6" stroke-linecap="round" stroke-linejoin="round"/>
-  <path id="leg_r" d="M 172.0 117.2 L 217.6 111.3 L 205.0 148.7 L 215.7 151.2" stroke="#0d9488" stroke-width="6" stroke-linecap="round" stroke-linejoin="round"/>
-  <path id="arm_r" d="M 93.2 149.2 L 122.8 144.1 L 152.3 139.0" stroke="#3a3f4b" stroke-width="6" stroke-linecap="round" stroke-linejoin="round"/>
+  <g id="leg_r">
+    <path d="M 172.0 117.2 L 217.6 111.3" stroke="#0d9488" stroke-width="6" stroke-linecap="round"/>
+    <path d="M 217.6 111.3 L 205.0 148.7" stroke="url(#grad-leg_r-1)" stroke-width="5.99159" stroke-linecap="round"/>
+    <path d="M 205.0 148.7 L 215.7 151.2" stroke="url(#grad-leg_r-2)" stroke-width="5.95646" stroke-linecap="round"/>
+  </g>
+  <g id="arm_r">
+    <path d="M 93.2 149.2 L 122.8 144.1" stroke="#3a3f4b" stroke-width="6" stroke-linecap="round"/>
+    <path d="M 122.8 144.1 L 152.3 139.0" stroke="#3a3f4b" stroke-width="6" stroke-linecap="round"/>
+  </g>
   <circle id="head" cx="75.0" cy="139.3" r="10" fill="white" stroke="#3a3f4b" stroke-width="6"/>
   <line id="nose" x1="78.1" y1="129.8" x2="80.2" y2="123.2" stroke="#3a3f4b" stroke-width="4" stroke-linecap="round"/>
   <g font-family="-apple-system, Helvetica, sans-serif" font-size="11" fill="#6b7180">