fix(presentation): prevent input blocking in multi-instance scenarios

[palmer-cl]

• Fixes a bug where mounting two SuperDoc instances on the same page blocked typing and could throw RangeError: Maximum call stack size exceeded
• Each PresentationEditor registers window-level capture listeners via PresentationInputBridge to reroute input from stale hidden ProseMirror editors
• With multiple instances, each bridge treated the other's editor as "stale," suppressed the real keystroke, and re-dispatched a synthetic event that the other bridge intercepted in turn — causing infinite recursion and blocked input
• Adds an instance-ownership check so stale rerouting only runs when the event originated from a hidden editor owned by the same SuperDoc instance
• Story-session editors (footnotes, headers/footers) within one instance still reroute correctly

[linear-code]

SD-3249

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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