[FEATURE] UIBridge: add open-in-new-tab action

[ScottKirvan]

Summary

Add an open-file-new-tab action to the UIBridge that opens a file in a new stacked tab, distinct from the existing open-file (same pane) and open-file-split (side-by-side split) actions.

Motivation

Currently there is no way for Claude to open a file in a new tab via the UIBridge. The open-file action reuses the current pane, and open-file-split creates a side-by-side split. A true "new tab" action would open the file in a new stacked tab — matching the behaviour of middle-clicking or Ctrl+clicking a link in Obsidian.

Proposed Behavior

New action:

@@CORTEX_ACTION {"action": "open-file-new-tab", "path": "Notes/MyNote.md"}

• Opens the file in a new stacked tab (not replacing the current tab, not creating a split)
• Consistent with Obsidian's native "open in new tab" behaviour