Speed up UI tests

[pascalpp]

Summary

• Replace repeated Preferences-window state reads in UI tests with UI-test-only state files.
• Move UI-test support out of AppDelegate into UITestSupport and an app-only extension.
• Remove redundant cursor interaction cycles while preserving cursor state coverage.

Why

The UI suite was spending time on repeated Preferences interactions and duplicated cursor action sequences. The new support helper lets tests observe app state through deterministic files, which keeps the suite faster and keeps test-only plumbing out of AppDelegate.

Validation

• xcodebuild -project "Free Ruler.xcodeproj" -scheme "Free Ruler" test -only-testing:FreeRulerUITests/FreeRulerUITests/testFloatShadowAndUnitKeyboardCommands
• xcodebuild -project "Free Ruler.xcodeproj" -scheme "Free Ruler" test -only-testing:FreeRulerTests
• xcodebuild -project "Free Ruler.xcodeproj" -scheme "Free Ruler" test -only-testing:FreeRulerUITests
• xcodebuild -project "Free Ruler.xcodeproj" -scheme "Free Ruler GitHub" build

[pascalpp]

Local UI test timing, measured with xcodebuild -project "Free Ruler.xcodeproj" -scheme "Free Ruler" test -only-testing:FreeRulerUITests.

Before is the branch base, 22de890; after is current PR head, 5fb1f79. Durations below are Xcode test execution durations, excluding build/package resolution time. The latest after run includes the cursor press-duration change from 0.4s to 0.2s.

Scope	Before	After	Delta
Full FreeRulerUITests target	15 tests / 148.1s	13 tests / 105.7s	-42.4s (-29%)
Cursor coverage	3 tests / 56.6s	1 test / 23.8s	-32.7s (-58%)
Cursor app launches	3	1	-2 launches
Cursor press duration	0.4s	0.2s	-0.2s per press
testFloatShadowAndUnitKeyboardCommands	9.8s	5.1s	-4.7s
testGroupedRulerToggleUngroupsAndHidesRequestedRuler	9.0s	6.7s	-2.4s
testGroupRulersKeyboardCommandUngroupsOnFirstAttempt	7.8s	5.4s	-2.4s

Cursor before total is the sum of the old grouped/horizontal/vertical cursor tests: 26.2s + 14.1s + 16.2s. The new combined cursor test keeps those cases as XCTContext activities inside one app launch.