Add the exercise reference library, animated exercise figures, and exercise categories

Exercise Library/ holds per-exercise reference docs (setup, cues,
mistakes, progressions) with SVG visuals and a Python-rendered motion
pipeline; Workouts/ExerciseFigure renders the bundled *.motion.json
rigs as animated stick figures on the exercise screen. Exercises gain
a warm-up/main-circuit category, timed exercises display hold time via
planSummary, and a completed exercise reopens to a check screen instead
of its timers.

Workouts/ExerciseFigure/ExerciseMotion.swift

@@ -0,0 +1,101 @@
+//
+// ExerciseMotion.swift
+// Workouts
+//
+// Copyright 2026 Rouslan Zenetl. All Rights Reserved.
+//
+
+import Foundation
+
+/// Codable mirror of the Exercise Library's rig data (see `Exercise Library/SYSTEM.md`).
+///
+/// A **body profile** is a table of bone lengths; a **motion script** is key frames of
+/// absolute joint angles (degrees, y-up: 0 = right, 90 = up, −90 = down), a pelvis
+/// `root` in 320×180 canvas coordinates, optional IK pins for planted hands/feet, and
+/// hold/tween timings. The app bundles verbatim copies exported by
+/// `render.py --export` into `Resources/ExerciseMotions/` — `body.json` plus one
+/// `<Exercise Name>.motion.json` per library entry.
+
+/// Bone lengths for one figure profile (`neutral` is the default).
+struct ExerciseBodyProfile: Codable {
+    let headR: Double
+    let neck: Double
+    let spine1: Double
+    let spine2: Double
+    let upperArm: Double
+    let foreArm: Double
+    let thigh: Double
+    let shin: Double
+    /// Offset separating left-limb attachments visually: `[dx, dy]` in canvas points.
+    let leftOffset: [Double]
+}
+
+/// One exercise's motion script: key frames plus the parts drawn in the accent color.
+struct ExerciseMotion: Codable {
+    let name: String
+    /// 1-based frame used for the static visual (unused by the animated renderer).
+    let primary: Int?
+    /// Parts (`arm_r`, `leg_l`, `spine`, …) drawn in the working accent color.
+    let working: [String]?
+    /// Limbs fully occluded in this view — never drawn.
+    let hide: [String]?
+    let frames: [MotionKeyFrame]
+}
+
+/// A key frame of absolute joint angles. Limbs listed in the motion's `hide` may be
+/// absent entirely; a two-element array is `[upper, lower]` bone angles.
+struct MotionKeyFrame: Codable {
+    /// Seconds held at this key frame (default 0.5).
+    let hold: Double?
+    /// Seconds animating to the *next* frame (default 0.6); the last frame tweens
+    /// back to the first, looping.
+    let tween: Double?
+    /// Pelvis position, canvas coordinates `[x, y]`.
+    let root: [Double]
+    /// Pelvis→mid and mid→neck angles.
+    let spine: [Double]
+    /// Head direction from the neck joint.
+    let neck: Double
+    /// Nose-tick direction (the belly is on that side).
+    let gaze: Double
+    let armR: [Double]?
+    let armL: [Double]?
+    let legR: [Double]?
+    let legL: [Double]?
+    /// IK targets for planted extremities, keyed `hand_r`/`hand_l`/`foot_r`/`foot_l`.
+    /// A pin present in two consecutive key frames stays planted through the tween.
+    let pins: [String: [Double]]?
+
+    enum CodingKeys: String, CodingKey {
+        case hold, tween, root, spine, neck, gaze, pins
+        case armR = "arm_r"
+        case armL = "arm_l"
+        case legR = "leg_r"
+        case legL = "leg_l"
+    }
+}
+
+/// Finds and decodes the bundled rig resources for an exercise, by exact name match
+/// against the exported `<Exercise Name>.motion.json` files.
+enum ExerciseMotionLibrary {
+    struct Resources {
+        let motion: ExerciseMotion
+        let body: ExerciseBodyProfile
+    }
+
+    /// The motion script plus the neutral body profile for `exerciseName`, or `nil`
+    /// when no bundled motion matches (most exercises have none — the caller keeps
+    /// its space empty).
+    static func resources(for exerciseName: String) -> Resources? {
+        guard
+            let motionURL = Bundle.main.url(forResource: exerciseName, withExtension: "motion.json"),
+            let bodyURL = Bundle.main.url(forResource: "body", withExtension: "json"),
+            let motionData = try? Data(contentsOf: motionURL),
+            let bodyData = try? Data(contentsOf: bodyURL),
+            let motion = try? JSONDecoder().decode(ExerciseMotion.self, from: motionData),
+            let profiles = try? JSONDecoder().decode([String: ExerciseBodyProfile].self, from: bodyData),
+            let body = profiles["neutral"]
+        else { return nil }
+        return Resources(motion: motion, body: body)
+    }
+}