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/onboarding/DurationStep.tsx

@@ -0,0 +1,59 @@
+"use client";
+
+import { Slider } from "@/components/ui/Slider";
+
+interface DurationStepProps {
+  duration: number;
+  onChange: (min: number) => void;
+}
+
+export function DurationStep({ duration, onChange }: DurationStepProps) {
+  return (
+    <div>
+      <h2 className="text-2xl font-bold text-zinc-100 mb-2">
+        Workout Duration
+      </h2>
+      <p className="text-zinc-400 mb-10">
+        How long do you want each workout to be? This is the total time
+        including warm-up, working sets, and rest periods.
+      </p>
+
+      {/* Big centered display */}
+      <div className="flex flex-col items-center justify-center py-12">
+        <div className="text-7xl font-bold text-accent tabular-nums mb-2">
+          {duration}
+        </div>
+        <div className="text-lg text-zinc-400">minutes</div>
+      </div>
+
+      {/* Slider */}
+      <div className="max-w-md mx-auto">
+        <Slider
+          min={20}
+          max={90}
+          value={duration}
+          onChange={onChange}
+          step={5}
+          label="Duration"
+          unit="min"
+        />
+      </div>
+
+      {/* Duration guide */}
+      <div className="mt-10 grid grid-cols-3 gap-4 text-center">
+        <div>
+          <div className="text-sm font-medium text-zinc-300">Quick</div>
+          <div className="text-xs text-zinc-500">20-30 min</div>
+        </div>
+        <div>
+          <div className="text-sm font-medium text-zinc-300">Standard</div>
+          <div className="text-xs text-zinc-500">40-60 min</div>
+        </div>
+        <div>
+          <div className="text-sm font-medium text-zinc-300">Extended</div>
+          <div className="text-xs text-zinc-500">70-90 min</div>
+        </div>
+      </div>
+    </div>
+  );
+}