Surface machine settings in the exercise library and refine machine rigs

Library detail screens now lead with the user's recorded machine settings
(per-split when they disagree, empty-state card for machine-based entries)
and append the weight progression chart. Starter seeds mark machine
exercises with an empty machineSettings list so the settings UI lights up
before first use. The figure rig gains a frontal body profile for face-on
machines, props that can ride mid joints (knees/elbows), and an
alternating four-frame Bird Dog loop.

Claude-Session: https://claude.ai/code/session_01LEoff8bXGBS83tK1c55Mf7

Exercise Library/render.py

@@ -57,7 +57,14 @@ LIMBS = {  # limb -> (attach joint, [bone length keys], pin key)
 
 ANGLE_KEYS = ["spine", "neck", "gaze", "arm_r", "arm_l", "leg_r", "leg_l"]
 
-JOINT_LIMB = {"hand_r": "arm_r", "hand_l": "arm_l", "foot_r": "leg_r", "foot_l": "leg_l"}
+# Prop joint refs -> (limb, chain index): extremities are index 2, mid joints
+# (elbows/knees) index 1, so equipment can ride either joint.
+JOINT_LIMB = {
+    "hand_r": ("arm_r", 2), "elbow_r": ("arm_r", 1),
+    "hand_l": ("arm_l", 2), "elbow_l": ("arm_l", 1),
+    "foot_r": ("leg_r", 2), "knee_r": ("leg_r", 1),
+    "foot_l": ("leg_l", 2), "knee_l": ("leg_l", 1),
+}
 
 
 def bodies():
@@ -244,17 +251,19 @@ def flip_props(props, width):
 
 
 def joint_points(geo, ref):
-    """Resolve a joint ref — `"hand_r"` or a `["hand_r", "hand_l"]` midpoint —
-    to (point, lower-bone unit direction). None when the limb isn't drawn."""
+    """Resolve a joint ref — `"hand_r"`, `"knee_l"`, or a midpoint list like
+    `["knee_r", "foot_r"]` — to (point, unit direction of the bone ending at
+    the first joint). None when the limb isn't drawn."""
     names = ref if isinstance(ref, list) else [ref]
     pts, direction = [], None
     for name in names:
-        limb = geo.get(JOINT_LIMB[name])
+        limb_name, idx = JOINT_LIMB[name]
+        limb = geo.get(limb_name)
         if not limb:
             return None, None
-        pts.append(limb[-1])
+        pts.append(limb[idx])
         if direction is None:
-            a, b = limb[-2], limb[-1]
+            a, b = limb[idx - 1], limb[idx]
             d = math.hypot(b[0] - a[0], b[1] - a[1]) or 1.0
             direction = ((b[0] - a[0]) / d, (b[1] - a[1]) / d)
     return ((sum(p[0] for p in pts) / len(pts),
@@ -487,7 +496,9 @@ def export_app_resources(folders):
 
 def render_exercise(folder, figure="neutral", flip=False):
     motion = load_motion(folder)
-    body = bodies()[figure]
+    # A motion may pin its own profile (e.g. "frontal": foreshortened legs for
+    # face-on seated machines); it wins over the CLI default.
+    body = bodies()[motion.get("figure", figure)]
     working = set(motion.get("working", []))
     hide = set(motion.get("hide", []))
     props = motion.get("props", [])
@@ -521,10 +532,11 @@ def contact_sheet(folders, figure="neutral", out=None):
     from PIL import Image, ImageDraw
 
     font = legend_font()
-    body = bodies()[figure]
+    profiles = bodies()
     cells = []
     for folder in folders:
         motion = load_motion(folder)
+        body = profiles[motion.get("figure", figure)]
         working, hide = set(motion.get("working", [])), set(motion.get("hide", []))
         props = motion.get("props", [])
         for i, kf in enumerate(motion["frames"], start=1):