feat(spec): add Motion & Micro-interaction section and motion tokens

[xkxx]

Add the ## Motion & Micro-interaction section and purpose-named motion YAML tokens to the DESIGN.md specification so design systems can define consistent motion choreography and export transition tokens.

Changes

• Add the ## Motion & Micro-interaction section (with aliases Motion & Micro-interactions and Motion) and motion token schema (duration, delay, timingFunction) to docs/spec.md and README.md.
• Parse and validate motion tokens (ms durations and CSS easing functions) in the linter model and include motion in omitted and token-summary rules.
• Map motion tokens to Tailwind theme extensions (transitionDuration, transitionDelay, transitionTimingFunction).
• Add unit and integration tests for ## Motion & Micro-interaction section ordering, motion token validation, and Tailwind export.