[codex] Fix mouse tick resume after ruler drag

[pascalpp]

Summary

Fixes #181 by making ruler window drags explicitly finish the mouse tick suspension path when AppKit's borderless-window drag loop returns.

Root Cause

PR #176 suppresses mouse ticks while a ruler is being dragged and expects the normal mouse-up responder path to resume them. For borderless movable panels, super.mouseDown(with:) can own the drag loop, so the controller may not receive a normal mouseUp after the drag. That leaves the controller in its dragging state and keeps tick resume behavior stuck until another click.

Changes

• Move ruler drag completion into RulerController.finishMouseDrag(with:).
• Have RulerWindow.mouseDown(with:) call that completion path once AppKit's drag loop returns and the left mouse button is no longer pressed.
• Add regression coverage that verifies both ruler ticks resume after the window-drag completion path.

Validation

• xcodebuild -project "Free Ruler.xcodeproj" -scheme "Free Ruler" -only-testing:FreeRulerTests/RulerCoreTests test
• xcodebuild -project "Free Ruler.xcodeproj" -scheme "Free Ruler" test

[Copilot]

Pull request overview

This PR fixes a regression where mouse tick updates could remain suspended after dragging a borderless ruler window, because AppKit’s borderless-window drag loop can prevent the controller from receiving a normal mouseUp. The change ensures the “drag finished” path is explicitly invoked once the drag loop returns, and adds regression tests covering tick resumption (including the paired/other ruler).

Changes:

• Extract drag completion into RulerController.finishMouseDrag(with:) and call it from mouseUp.
• In RulerWindow.mouseDown(with:), after super.mouseDown(with:) returns, detect that the left mouse button is no longer pressed and explicitly finish the drag.
• Add regression tests verifying mouse ticks resume after drag-loop completion and don’t resume during grouped-child move notifications while the mouse is still down.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
FreeRulerTests/RulerCoreTests.swift	Adds regression coverage for tick resumption after drag-loop completion and for grouped-move behavior during an active drag.
Free Ruler/RulerWindow.swift	Ensures the drag-completion path is triggered after AppKit’s borderless drag loop returns and the mouse button is up.
Free Ruler/RulerController.swift	Centralizes drag completion in finishMouseDrag(with:), adjusts move-resume gating to account for left-button-down state, and simplifies tick enabling.

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