Revise Haptics explainer based on CSSWG F2F feedback (#1302)

* Revise Haptics explainer to include declarative method

* [Haptics] formatting & clarifications

* Update haptic-feedback intensity values to accept percentages in explainer

* Focus on css animation/transition as primary

* clean up

* Clean up

* Enhance explainer with platform-native feedback mappings for haptic effects

* typo

* Refine haptic feedback descriptions and enhance CSS integration for transitions

* Better framing for pseudo-class model

* Refine alternatives considered section for clarity and detail

* Clarify behavior of transition-haptic-effect and refine pseudo-class haptic model descriptions

* Refactor to have pseudo-class approach in primary

* Remove section on transition start haptics for clarity and focus on custom haptic effects

* Fix formatting inconsistencies in explainer document

* Add note on potential use of :snapped pseudo-class for scroll-snap haptics

* Update Haptics/explainer.md

Co-authored-by: Kevin Babbitt <[email protected]>

* correct author link

* Refine haptics alternatives and selector-trigger framing

* Move `scroll-snap-haptic` to alternative considered assuming :snapped will ship

* Clarify haptic effect options and add specificity conflict resolution details in explainer.md

* Clarify haptic feedback feature detection and fallback requirements in explainer.md

* Add appendix for CSS alternatives with code examples in explainer.md

* Clarify haptic feedback target selection and refine API behavior for device capability checks

* Clarify `@haptic-trigger` behavior by specifying that haptics fire only on selector start-matching, and update related documentation for consistency.

* fix(explainer): clarify note on `:snapped` pseudo-class implementation status

* fix(explainer): clarify haptic feedback behavior and selector coverage in the documentation

* New nested at-rule method

* fix(explainer): update authors list to include Kevin Babbitt

* fix(explainer): refine descriptions for animation-trigger and transition-coupled haptic models

* Update Haptics/explainer.md

Co-authored-by: Kevin Babbitt <[email protected]>

* Update Haptics/explainer.md

Co-authored-by: Kevin Babbitt <[email protected]>

* Update Haptics/explainer.md

Co-authored-by: Kevin Babbitt <[email protected]>

* Update Haptics/explainer.md

Co-authored-by: Kevin Babbitt <[email protected]>

* fix(explainer): clarify parent selector behavior in haptic API descriptions

* fix(explainer): clarify behavior of `@haptic` with initial style computation

* Revert "fix(explainer): clarify parent selector behavior in haptic API descriptions"

This reverts commit 2396c0f.

* fix(explainer): add support for nesting `@haptic` inside `@keyframes` for multi-step choreography

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Co-authored-by: Kevin Babbitt <[email protected]>

Author: liminzhu