[codex] Add bounded markup motion hooks

[cssbruno]

Summary

• Fixes [Markup] Bounded g:transition/g:animate for enter/leave animations #503.
• Adds bounded g:transition and g:animate directives for client g:if branches and keyed client g:for rows.
• Emits motion data attributes and toggles compiler-owned enter/leave/move classes in the island runtime, including interrupted leave handling.
• Updates docs, stability metadata, diagnostics text, conformance coverage, and the feature spec/plan.

Verification

• go test ./internal/viewparse ./internal/viewrender ./internal/viewanalysis ./internal/clientrt ./internal/buildgen ./internal/lang ./internal/diagnostics
• go build ./cmd/gowdk
• go test ./...
• scripts/test-go-modules.sh

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Do not truncate user-defined motion durations

When a user-defined transition or animation lasts longer than 240ms, this timeout fires before the browser's transitionend/animationend, which clears the motion classes and removes leaving nodes early. The new docs say motion timing lives in user/addon CSS and do not impose a duration cap, so a normal transition: opacity 500ms leave animation would be cut off at 240ms. Compute the fallback from the element's computed transition/animation durations and delays, or otherwise avoid letting the fallback preempt real end events.

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