Consolidate desktop motion primitives

[mahanti]

Summary

• add semantic duration aliases for the existing 150ms and 200ms motion timings
• replace all shared and feature transition-all usages with explicit transition properties
• collapse semantic durations under reduced motion

This is roadmap item 11 from the BlockUI foundations audit. It preserves the current timing values while making motion intent explicit and preventing unrelated properties from animating. Agentation is not included in this branch.

Related issue

None found.

Testing

• full pre-push desktop check, TypeScript typecheck, and 4,000+ unit test suite
• focused motion contract tests, including reduced motion
• production build and repository lint/checks

Screenshots are not included because this is a timing/property contract change with no intended static visual delta.

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