[robinlopez]

Jira: FSHSP-253. Port of the Angular starter's FSHSP-252 (4sh/starter-angular#181), same token names and values. Figma variables: FSHSP-254.

Motion becomes a token, like colour: --transition-* stay the primitives (no rename, nothing deprecated), a new motion collection holds recipes by usage that alias them, and the kit reads the recipes. Timing is unchanged outside reduced motion.

• Typed tokens (scripts/tokens.build.mjs): DTCG duration, cubicBezier and dimension values get their CSS form; a unitless duration or a curve whose x leaves [0, 1] fails the build; numbers rounded to 6 significant digits; a mode mapped to null is not emitted.
• Figma sync: transition/* typed TIMING / EASING under the same names (curves now read cubic-bezier(), same curve); new motion.json with modes Standard / Reduced.
• Recipes in the kit: control-transition takes toggle for properties that move and hover for the rest; motion-transition reads toggle; presets, utils.overlay-motion and useUiMotion classes read overlay-in / overlay-out; speed-dial reads stagger. Each recipe falls back to the primitive used before, so --transition-* and --ui-control-transition-* overrides still apply.
• Reduced motion: Reduced emitted under (prefers-reduced-motion: reduce) instead of the 0.01ms !important rules: presets become 80ms fades, movement shortens, colour changes keep their duration. data-motion="off" unchanged.
• Tooling: pnpm motion:check in docs:config:check, with the 3 loop exceptions (skeleton, spinner, progress-bar).
• Docs: Foundations / Motion, collections tables, AGENTS.md, docs/DECISIONS.md, and in docs/DUAL-ENGINE.md the invariant "same motion primitive and recipe names in both stacks".

Parity checked against the Angular branch: generated _tokens-motion.scss and _tokens-transitions.scss are identical, motion:check passes.