feat: add experimental motion and agent-feedback foundations

[jaavid]

Closes #12

What changed

• adds semantic motion tokens and MotionProvider with system/forced reduced-motion preferences
• adds experimental AsyncStatus, Progress, StatusIndicator, AnimatedNumber, and an optional CSS-only AgentStatusOrb
• keeps experimental CSS opt-in so stable core styles do not grow when unused
• adds Persian RTL, English LTR, dark, and forced reduced-motion Storybook coverage
• adds progress boundary tests plus low-end mobile performance, layout-stability, accessibility, and provenance guidance
• advances the component maturity matrix from Proposed/Deferred to Experimental

Guardrails

• no runtime, Canvas, WebGL/WebGPU, or motion-library dependency
• no motion-only meaning and no fabricated reasoning UI
• AgentReady validation remains required before Candidate/Stable promotion

---

^{Need help on this PR? Tag @codesmith with what you need. Autofix is enabled.}

[cloudflare-workers-and-pages]

Deploying design-system with    Cloudflare Pages

Latest commit:	7294efa
Status:	✅  Deploy successful!
Preview URL:	https://fbc1dc55.design-system-dby.pages.dev
Branch Preview URL:	https://feat-experimental-agent-feed.design-system-dby.pages.dev

View logs