Add 17 warm-up, stretch, and mobility exercises with new starter splits

The library grows to 64 exercises: arm circles, torso twist, leg
swings, hip and neck mobility, marching, calf raises, and a full
stretching set (forward fold, quad, calf, chest, triceps, hip flexor,
butterfly, cobra, child's pose), each with an authored motion rig and
reference page. Eight new starter splits join the catalog — Upper and
Lower Body Warm-Up, Morning Wake-Up, Morning Mobility, Full Body
Stretch, Evening Stretch, Free Weight Basics, and Full Body Machines —
regenerated deterministically at split schema v3 with fixed ULIDs.

Claude-Session: https://claude.ai/code/session_01HJDQQDA9QdP8zByg43H5v3

Exercise Library/COVERAGE.md

@@ -33,12 +33,13 @@ it is a considered exclusion, not a gap.
 | Elbow extension | Tricep Press, Triceps Pushdown | — | Dip |
 | Shoulder raise (lateral/rear) | Rear Delt Fly | Lateral Raise | — |
 | Hip abduction / adduction | Abductor, Adductor | — | — |
-| Calf | Calfs | — | — |
+| Calf | Calfs | — | Standing Calf Raise |
 | Core anti-extension | — | — | Plank, Dead Bug, Hollow Body Hold |
 | Core rotation / anti-rotation | Rotary | — | Bird Dog |
 | Core lateral | — | — | Side Plank |
 | Core flexion | Abdominal | — | Crunch, Reverse Crunch, Leg Raises |
-| Mobility / warm-up | — | — | Cat-Cow *(morning wake-up set: next phase)* |
+| Mobility / warm-up | — | — | Cat-Cow, March in Place, Leg Swings, Neck Rolls, Arm Circles, Torso Twist, Standing Side Bend, Hip Circles |
+| Static stretch | — | — | Standing Forward Fold, Standing Quad Stretch, Standing Calf Stretch, Chest Opener, Overhead Triceps Stretch, Kneeling Hip Flexor Stretch, Butterfly Stretch, Cobra Stretch, Child's Pose |
 
 ## Gym-floor census
 
@@ -57,6 +58,8 @@ entries) a user logging by that station's name will find.
 | Pull-up / dip station (incl. assisted machine) | Pull-Up, Dip |
 | Dumbbell rack | Dumbbell Bench Press, Dumbbell Fly, Dumbbell Row, Dumbbell Shoulder Press, Dumbbell Curl, Lateral Raise, Goblet Squat, Lunge |
 | Floor / mat | Bodyweight Squat, Push-Up, Crunch, Glute Bridge, Plank, Side Plank, Bird Dog, Dead Bug, Hollow Body Hold, Leg Raises, Reverse Crunch, Cat-Cow |
+| Open floor (warm-up / mobility) | March in Place, Leg Swings, Neck Rolls, Arm Circles, Torso Twist, Standing Side Bend, Hip Circles, Standing Calf Raise |
+| Stretching mat (cool-down) | Standing Forward Fold, Standing Quad Stretch, Standing Calf Stretch, Chest Opener, Overhead Triceps Stretch, Kneeling Hip Flexor Stretch, Butterfly Stretch, Cobra Stretch, Child's Pose |
 
 ## Considered exclusions (the "most gyms" line)
 
@@ -73,8 +76,13 @@ entries) a user logging by that station's name will find.
   ("barbell or dumbbells" in their pages), not separate entries.
 - **Kettlebells, T-bar row, pullover machine, cardio equipment** — out; not
   strength stations found in most gyms (cardio is out of the app's scope).
-- **Morning wake-up mobility set** (neck rolls, arm circles, …) — deliberately
-  deferred to the next library phase; Cat-Cow holds the mobility row today.
+- **Morning wake-up mobility & stretching set** — landed. Dynamic warm-up
+  drills (March in Place, Leg Swings, Neck Rolls, Arm Circles, Torso Twist,
+  Standing Side Bend, Hip Circles) now fill the mobility row alongside Cat-Cow,
+  and a static-stretch group (Standing Forward Fold, Standing Quad/Calf
+  Stretch, Chest Opener, Overhead Triceps Stretch, Kneeling Hip Flexor Stretch,
+  Butterfly Stretch, Cobra Stretch, Child's Pose) covers the cool-down mat.
+  Standing Calf Raise adds the bodyweight calf cell.
 
 ## Standing exercises and `camera.zoom`