workout generator audit: rules engine, structure rules, split patterns, injury UX, metadata cleanup

- Add rules_engine.py with quantitative rules for all 8 workout types
- Add quality gate retry loop in generate_single_workout()
- Expand calibrate_structure_rules to all 120 combinations (8 types × 5 goals × 3 sections)
- Wire WeeklySplitPattern DB records into _pick_weekly_split()
- Enforce movement patterns from WorkoutStructureRule in exercise selection
- Add straight-set strength support (single main lift, 4-6 rounds)
- Add modality consistency check for duration-dominant workout types
- Add InjuryStep component to onboarding and preferences
- Add sibling exercise exclusion in regenerate and preview_day endpoints
- Display generator warnings on dashboard
- Expand fix_rep_durations, fix_exercise_flags, fix_movement_pattern_typo
- Add audit_exercise_data and check_rules_drift management commands
- Add Next.js frontend with dashboard, onboarding, preferences, history pages
- Add generator app with ML-powered workout generation pipeline
- 96 new tests across 7 test modules

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

werkout-frontend/components/ui/Spinner.tsx

@@ -0,0 +1,37 @@
+type SpinnerSize = "sm" | "md" | "lg";
+
+interface SpinnerProps {
+  size?: SpinnerSize;
+  className?: string;
+}
+
+const sizePx: Record<SpinnerSize, number> = {
+  sm: 16,
+  md: 24,
+  lg: 40,
+};
+
+const borderWidth: Record<SpinnerSize, number> = {
+  sm: 2,
+  md: 3,
+  lg: 4,
+};
+
+export function Spinner({ size = "md", className = "" }: SpinnerProps) {
+  const px = sizePx[size];
+  const bw = borderWidth[size];
+
+  return (
+    <span
+      role="status"
+      aria-label="Loading"
+      className={`inline-block animate-spin rounded-full ${className}`}
+      style={{
+        width: px,
+        height: px,
+        border: `${bw}px solid rgba(63,63,70,0.6)`,
+        borderTopColor: "#39FF14",
+      }}
+    />
+  );
+}