feat(input): migrate to extend textarea

[msmps]

Summary

Refactor InputRenderable to extend TextareaRenderable, eliminating ~200 lines of duplication.

Key changes:

• Input now inherits text editing, cursor management, and key binding logic from Textarea
• Action names aligned with Textarea conventions (line-home, line-end, backspace, delete)
  • BREAKING CHANGE?

Test Plan

• Existing Input tests updated and passing
• Manual test

[pkg-pr-new]

@opentui/core

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@opentui/react

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@opentui/solid

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@opentui/core-darwin-arm64

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@opentui/core-darwin-x64

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@opentui/core-linux-arm64

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@opentui/core-linux-x64

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@opentui/core-win32-arm64

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@opentui/core-win32-x64

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commit: d7fe746

[Hona]

This would be a good pr to try my snapshot testing on 👀

[msmps]

This would be a good pr to try my snapshot testing on 👀

Take it away @Hona 🙌