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 Watch App/Views/ExerciseProgressView.swift

@@ -79,6 +79,11 @@ struct ExerciseProgressView: View {
     /// transient TabView snap-to-0, so it isn't reset on open.
     @State private var startsResumed: Bool
 
+    /// True when the exercise was already completed when this screen opened — it shows a
+    /// static Completed page instead of dropping back into the timer flow. Fixed at init
+    /// so completing the exercise from inside the flow doesn't swap the page mid-dismiss.
+    @State private var startsCompleted: Bool
+
     /// Forces the starting page (used only by the DEBUG screenshot host). When set it
     /// also suppresses the Ready page so the index is a plain work/rest cycle offset.
     private let debugInitialPage: Int?
@@ -102,6 +107,7 @@ struct ExerciseProgressView: View {
         // set and re-asserts that page past the TabView's snap-to-0 on first layout.
         let ready = debugInitialPage == nil
         _startsResumed = State(initialValue: ready && !notStarted)
+        _startsCompleted = State(initialValue: ready && log?.status == WorkoutStatus.completed.rawValue)
 
         let base = ready ? 1 : 0
         // Resume on the first unfinished set's work page (clamped to the last set).
@@ -182,6 +188,14 @@ struct ExerciseProgressView: View {
     }
 
     var body: some View {
+        if startsCompleted {
+            CompletedPhaseView()
+        } else {
+            flowBody
+        }
+    }
+
+    private var flowBody: some View {
         TabView(selection: $currentPage) {
             ForEach(0..<totalPages, id: \.self) { index in
                 page(for: index)
@@ -727,6 +741,22 @@ private extension View {
     }
 }
 
+// MARK: - Completed Phase
+
+/// Shown instead of the run flow when the exercise was already completed on open.
+private struct CompletedPhaseView: View {
+    var body: some View {
+        VStack(spacing: 8) {
+            Image(systemName: "checkmark.circle.fill")
+                .font(.system(size: 56))
+                .foregroundStyle(.green)
+            Text("Completed")
+                .font(.system(.title3, design: .rounded, weight: .heavy))
+        }
+        .frame(maxWidth: .infinity, maxHeight: .infinity)
+    }
+}
+
 // MARK: - Ready Phase
 
 private struct ReadyPhaseView: View {