feat(skills): align easing docs with motion doctrine, add baked springEase (#1989)

* feat(skills): align easing docs with motion doctrine, add baked springEase

The easing adapter contradicted the workflow doctrine: it taught a
power2.out entrance default and pitched back/elastic as playful
defaults, while motion-language.md says power3 / smooth-beats-bouncy.
A worker following the adapter produced exactly the flat, cheap motion
users complain about.

- gsap-easing-and-stagger: power3.out becomes the documented house
  default; back/elastic/bounce capped as RARE playful-only; new
  "Spring Eases (baked physics, seek-safe)" section — closed-form
  damped-spring ease springEase(response, dampingFraction), measured
  damping ladder, response/duration table, craft notes
- gsap-timeline-and-labels: last leftover power2.out default -> power3
- spring-pop-entrance: exact-physics option (zeta=1) for the settle;
  playful variant now prefers spring zeta 0.6-0.7 over back.out
- motion-language x3 (product-launch-video, faceless-explainer,
  pr-to-video): doctrine "Smooth beats bouncy" wired to the baked
  springEase — real physics, same doctrine, not a license for bounce

Verified with node + GSAP 3.15: zeta=1 strictly monotone with zero
overshoot; scrambled out-of-order seeks return bit-identical values;
ease(0)=0 and ease(1)=1 exact; snippet re-extracted from the published
markdown and re-run.

* chore: format README.md (landed unformatted on main; unblocks the repo-wide Format check)

skills/hyperframes-animation/adapters/gsap-timeline-and-labels.md

@@ -7,7 +7,7 @@ HyperFrames is a seek-driven runtime. Build one paused timeline per composition,
 ```javascript
 const tl = gsap.timeline({
   paused: true,
-  defaults: { duration: 0.5, ease: "power2.out" },
+  defaults: { duration: 0.5, ease: "power3.out" },
 });
 
 tl.to(".a", { x: 100 }).to(".b", { y: 50 }).to(".c", { opacity: 0 });