feat(preview): add pinch-to-zoom and keyboard zoom shortcuts

[Isioma20]

Component / Package Name:

Preview

This PR contains:

• bugfix
• feature
• refactor
• documentation
• other

Are tests included?

• yes (bugfixes and features will not be merged without tests)
• no

Breaking Changes?

• yes (breaking changes will not be merged unless absolutely necessary)
• no

If yes, please include "BREAKING CHANGES:" in the first commit message body, followed by a description of what is breaking.

List any relevant issue numbers:

Description

• Adds pinch-to-zoom (trackpad) and Ctrl+scroll support for continuous canvas zoom
• Adds Cmd+scroll for step-based zoom
• Adds Cmd+/Cmd- keyboard shortcuts for zoom in/out and Cmd+0 to reset to 100%
• All interactions anchor zoom to cursor position for natural feel
• Prevents browser native zoom from interfering

Video Demo:
https://github.com/user-attachments/assets/7a943e43-e447-4ff4-bdd1-b4377dfbe0bb

Test plan

• Pinch to zoom on trackpad zooms canvas smoothly
• Ctrl + mouse scroll zooms continuously
• Cmd + mouse scroll zooms in steps
• Cmd+= zooms in, Cmd+- zooms out, Cmd+0 resets to 100%
• Zoom anchors to cursor position (content stays focused where you're looking)
• Header zoom buttons still work as before
• Z+click / Z+Alt+click zoom still works
• Templates panel and tool panel are excluded from zoom gestures
• Zoom stays clamped within bounds