[Refactor] useAbsolutePosition composable

[huchenlei]

This PR introduces a new composable useAbsolutePosition to handle absolute positioning calculations for elements on the LiteGraph canvas. The main changes involve extracting the positioning logic from TitleEditor.vue into a reusable composable that manages the conversion of canvas coordinates to client coordinates, handling scaling, and maintaining the position state. The TitleEditor component has been simplified by leveraging this new composable, replacing the manual style object initialization and coordinate calculations with cleaner, more maintainable code. The composable accepts a PositionConfig interface for position and size, along with optional scale and extra style properties, making it more flexible for reuse across different components that need canvas-to-screen coordinate conversion.

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