feat(movers): add configurable grid snapping and sliding AABB collision solver.

[TheMapperJS]

Description

This PR adds two highly requested quality-of-life options directly to the /moveui popup panel: Grid Snapping and Mover Collision. These features significantly enhance the layout customization experience, making UI alignment clean, physical, and satisfying.

Key Features

1. Configurable Grid Snapping (Drag & Drop):

   • Snaps movers to ElvUI's active visual grid lines (ElvUIGrid) in real-time during dragging and enforces a final, mathematically perfect grid snap upon release.
   • Snapping step sizes update dynamically (width / gridSize) when the grid size is changed in the move mode popup.

2. 2D Sliding AABB Mover Collision:

   • Implements Axis-Aligned Bounding Box (AABB) collision resolution between active movers.
   • Uses minimum penetration depth resolution axis-by-axis, allowing frames to slide smoothly along each other's boundaries rather than overlapping, sticking, or "jumping" across the screen.
   • Screen parent containers (such as UIParent, ElvUIParent, and WorldFrame) are filtered out of the loop so movers only block against other actual layout frames.

3. Smart Resolution & Scaling conversions:

   • Converts coordinates dynamically between individual frame-scale and global UIParent-scale. Snapping and collision boundaries remain pixel-perfect even if custom scales are applied to specific mover frames.

4. Safety & Native Hooks:

   • Sticky Frames Integration: ElvUI's native edge-to-edge frame sticky-snapping takes priority over grid-snapping when frames are close, preserving alignment habits.
   • Shift Key Bypass: Pressing the Shift key while dragging temporarily bypasses all snapping and collision rules for custom overlapping layouts.
   • Persistent Profiles: Saved under E.db.general.gridSnap and E.db.general.moverCollision with defaults set to true.

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Files Modified

• Profile.lua: Registered profile defaults for gridSnap = true and moverCollision = true under P.general.
• Config.lua: Expanded /moveui popup window height (from 190 to 215) and added two vertically stacked, styled checkboxes for "Grid Snapping" and "Mover Collision".
• LibSimpleSticky.lua: Implemented IsOverlapping and ResolveCollisions sliding solvers, and hooked grid snapping and collision checks inside StickyFrames:GetUpdateFunc().
• Movers.lua: Hooked StopMoving(frame) to enforce final snap calculations and commit the exact snapped positions to the layout database to prevent drift on /reload.