perf(react-compiler): enable useSafeTimeout

[joshblack]

Closes #

Enable React Compiler for useSafeTimeout as the first entry in our low-risk migration stack. Our migration report identifies the cleanup's ref access as the blocker.

Changelog

New

Changed

• Capture the timer Set when the effect runs so cleanup does not read through the ref. The Set stays shared with both timer callbacks, including timers registered after the effect.
• Remove the compiler exclusion and add a minor changeset, matching our recent compiler rollout.

Removed

Rollout strategy

• No changes needed in github/github-ui
• Needs changes in github/github-ui
• Ships with feature flag(s)
• Not sure
• None

[changeset-bot]

🦋 Changeset detected

Latest commit: 6d6cbe0

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@primer/react	Minor

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[github-actions]

⚠️ Action required

👋 Hi, this pull request contains changes to the source code that github/github-ui depends on. If you are GitHub staff, test these changes with github/github-ui using the integration workflow. Check the integration testing docs for step-by-step instructions. Or, apply the integration-tests: skipped manually label to skip these checks.

[joshblack]

Combined into #8555 so we can review these small compiler migrations in one PR.