Default suggestion fade to fastest speed

[FuJacob]

Summary

Set the default suggestion fade duration to the fastest Appearance-slider tick (0.05 seconds) so new installs start with the most responsive fade-in behavior.

Validation

• swiftlint lint --quiet — exit 0.
• xcodebuild -project Cotabby.xcodeproj -scheme Cotabby -destination 'platform=macOS' -derivedDataPath build/DerivedData CODE_SIGNING_ALLOWED=NO -jobs 1 build-for-testing — TEST BUILD SUCCEEDED.
• xcodebuild -project Cotabby.xcodeproj -scheme Cotabby -destination 'platform=macOS' -derivedDataPath build/DerivedData CODE_SIGNING_ALLOWED=NO test-without-building -only-testing:CotabbyTests/SuggestionSettingsStoreTests — TEST EXECUTE SUCCEEDED, 42 tests, 0 failures.

Linked issues

None.

Risk / rollout notes

Low risk. This affects only users without a persisted fade-speed preference; saved user settings continue to win. No schema, project, or runtime changes.

Greptile Summary

This PR makes the default suggestion fade-in speed faster.

• Sets the default fade-in duration to 0.05 seconds.
• Updates the setting comment to describe the fastest slider tick.
• Updates the default-duration test expectation.

Confidence Score: 4/5

The changed default path has one contained reset behavior issue.

• Missing-key loads use the new fastest duration as intended.
• Persisted user values continue to win as intended.
• Resetting defaults can keep an old persisted fade duration and skip the new default.

Cotabby/Support/SuggestionSettingsStore.swift

Important Files Changed

Filename	Overview
Cotabby/Support/SuggestionSettingsStore.swift	Changes the default fade-in duration to the fastest supported tick.
CotabbyTests/SuggestionSettingsStoreTests.swift	Updates the default fade-in duration test to expect the fastest tick mapping.

_{Reviews (1): Last reviewed commit: "Default suggestion fade to fastest speed" | Re-trigger Greptile}

Greptile also left 1 inline comment on this PR.

[greptile-apps]

Reset Keeps Stale Duration

When a user already has cotabbyFadeInDurationSeconds persisted at the old 0.10 value, reset-to-defaults does not remove that key, so load() keeps reading the stale value instead of this new 0.05 default. The visible result is that resetting Appearance settings can leave the fade speed on the old second-fastest tick instead of the new fastest default.