Add animation speed setting

[austin-smith]

What Changed

• New Animation Speed setting — Normal / Fast / Instant — at the bottom of the Gameplay settings section on iOS and macOS (shared row; navigation-link picker on iOS, pop-up on macOS).
• New Animation/MotionPolicy.swift: the speed catalog plus a single policy that scales every gameplay animation and completion delay. The system Reduce Motion setting clamps to instant regardless of the chosen speed.
• Every gameplay animation routes through the policy: board move springs, tap-move and drag-drop flights, invalid-drop returns, tilt settles, draw and tableau-deal flights, undo flights, card flips, and the drop-target/hint highlights. Each asyncAfter completion scales through the same policy with the same base duration, so flights and their cleanup cannot drift apart.
• The win celebration deliberately ignores the speed setting — it is a reward, not a wait — but Reduce Motion suppresses it: at win time it presents the settled end state the relaunch path already uses, and a Reduce Motion toggle mid-cascade lands the cards immediately via the same shared path.
• The hint wiggle keeps its normal pace on Fast (an affordance, not a wait) and is suppressed on Instant; the hint highlight still marks the cards.

Why

Solitaire animations sit directly in the play loop — every draw, move, undo, and auto-finish has a fixed duration the player waits through. Players who play fast want the pace to match, and motion-sensitive players get Reduce Motion honored for the first time, including the full-screen win cascade.

Validation

• Video frame-diff on the tap-move flight per speed: Normal = 8-frame flight + 12-frame flip (identical rhythm to before), Fast = 4 + 7 frames, Instant = single-frame changes with the move and flip applied and the end state correct.
• Reduce Motion with the setting on Normal: no motion, confirming the clamp wins over the setting.
• Draw at Instant: three cards land already fanned, stock count correct, no stranded overlay cards.
• Live binding: switching to Instant in the settings sheet took effect on the next move without relaunch.
• Full unit suite on macOS: 559 tests, 0 failures. macOS and iOS builds green; verified interactively in the iOS simulator and the macOS app.

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