feat: add path autocomplete in new session pane

[daulet]

Description

Add Tab completion in Path field of New session pane. While focus is on the path field Tab is overridden to do complete path rather than switch to next field.

PR Type

• New Feature
• Bug Fix
• Refactor
• Documentation
• Infrastructure / CI

Checklist

• I understand the code I am submitting
• New and existing tests pass
• Documentation was updated where necessary
• For UI changes: included screenshot or recording

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• AI was used for drafting/refactoring
• This is fully AI-generated

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[njbrake]

If tab is used for autocomplete then how do I advance to the next row?

[njbrake]

@daulet Thank you for the PR: I created #329 to help give the feature you want, which I agree is useful, but with different semantics: suggestions show inline and you can accept them with the right arrow or end key, so that we don't have to overload the tab button