deps: replace vendored refresh_rate 1.0.2 with upstream 2.0.1 #1584

Summary

third_party/refresh_rate is a vendored copy of refresh_rate 1.0.2 kept only for two build fixes. Upstream 2.0.1 appears to fix both natively, so the fork can likely be dropped in favour of refresh_rate: ^2.0.1.

Why the fork exists vs. 2.0.1

App compatibility

Only lib/core/motion/display_refresh_service.dart uses the package.

• RefreshRate.enable() now returns Future<RateRequestResult>; we call it unawaited (wrap in unawaited(...) if the lint is on).
• showHz() and info.{currentRate,maxRate,isVariableRefreshRate} are source-compatible.
• DisplayRefreshService.currentHz / maxHz have no other callers.

Behaviour changes: on Linux maxRate is 0.0 (was max across monitors) and unknown values no longer fall back to 60 Hz. info is populated asynchronously, so the first debug log may show 0 Hz.

Tasks

• Verify the package publisher: repository moved from qoder-official/refresh_rate to afewgoodcoders/refresh_rate while the Android package is still in.qoder.refresh_rate. Confirm it is a legitimate transfer and skim the native diff 1.0.2 → 2.0.1 (Windows and macOS changed too).
• pubspec.yaml: refresh_rate: ^2.0.1, remove the refresh_rate entry from dependency_overrides.
• Delete third_party/refresh_rate/ and update third_party/README.md if it references it.
• CI green on Linux (-Werror), Windows and macOS.
• Follow-up, separate PR: reconsider flutter.config.enable-swift-package-manager: false. It disables SPM for all plugins, not just this one.

Fallback

If the Linux -Werror build or Windows/macOS breaks on upstream 2.0.1, keep the fork and re-vendor 2.0.1 with only the needed patch.

Found during the dependency review.