fix issue #2713: adding support for alt+ctrl+h to delete backward word

[vinaybantupalli]

This pr addresses the fix for #2713

Changes:

• Added key handler for Alt+Ctrl+H → delete_backward_word()
• Added test coverage in delete_backward_word_alt_keys() that verifies both:
  • Standard Alt+Backspace binding continues to work
  • New Alt+Ctrl+H binding works correctly for backward word deletion

Testing:

The test ensures both key combinations produce identical behavior:

• Delete the previous word from "hello world" → "hello "
• Cursor positioned correctly after deletion

Backward Compatibility:

This change is backward compatible - existing Alt+Backspace functionality remains unchanged while adding support for the terminal-specific Alt+Ctrl+H variant

[github-actions]

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[vinaybantupalli]

I have read the CLA Document and I hereby sign the CLA

[nornagon-openai]

Suggested change

	modifiers,
	..
	} if modifiers == (KeyModifiers::CONTROL | KeyModifiers::ALT) => {
	modifiers: KeyModifiers::CONTROL | KeyModifiers::ALT,
	..
	} => {

[vinaybantupalli]

@nornagon-openai tried that.

compiler is not treating that as a bitwise OR, but as a pattern alternation operator (basically OR).
So, either ctrl+h, or alt+h can trigger it, which we don't want.
The match guard is a comparison to bitwise OR, so it works for us.

warning: unreachable pattern
   --> tui/src/bottom_pane/textarea.rs:249:15
    |
234 | /             KeyEvent {
235 | |                 code: KeyCode::Char('h'),
236 | |                 modifiers: KeyModifiers::CONTROL | KeyModifiers::ALT,
237 | |                 ..
238 | |             } => self.delete_backward_word(),
    | |_____________- matches all the relevant values
...
249 |               | KeyEvent {
    |  _______________^
250 | |                 code: KeyCode::Char('h'),
251 | |                 modifiers: KeyModifiers::CONTROL,
252 | |                 ..
253 | |             } => self.delete_backward(1),
    | |_____________^ no value can reach this
    |
    = note: `#[warn(unreachable_patterns)]` on by default

[vinaybantupalli]

added another test (ctrl_h_backspace) for simple CTRL+H to backspace conversion, both these tests are failing if I do modifiers: KeyModifiers::CONTROL | KeyModifiers::ALT, using match's pattern matching

[nornagon-openai]

ah, makes sense. thanks for checking!

[nornagon-openai]

overall happy w/ this change, just a couple of nits.

[nornagon-openai]

I think these aren't required as they're already imported at the top level, right?

[vinaybantupalli]

yeah. removed.
I just copied from the test above :P

[nornagon-openai]

this test would be better if the "l" wasn't repeated, maybe change the text to be "abcdef" instead?

[vinaybantupalli]

yeah. makes sense.