feat(core): Add in functionality for double-click word selection and triple-click line selection

[Karvy-Singh]

Adds multi-click mouse selection support for edit-buffer renderables.
(solves #74 and #744 )

Behavior:

• Double-click selects the clicked word.
• Triple-click selects the clicked line.
• Multi-click detection uses a 500ms threshold (as 200-500ms is considered the common metric).
• Clicks must be on the same target, same button, and same coordinates to count as a multi-click.
• Punctuation is treated as a word boundary, so Emacs-style) selects only the clicked word segment, for example Emacs or style.
• Whitespace clicks do not select surrounding words.
• Underscores are treated as word characters, so foo_bar is selected as one word.
• Ctrl-click behavior is unchanged.
• Normal single-click drag selection behavior is unchanged.

Notes:

• The implementation is kept close to the existing left mouse down selection branch.
• Added focused regression tests for double-click word selection, triple-click line selection, punctuation boundaries, first-letter clicks, and whitespace clicks.
• Other file changes are formatting-only from bun fmt.

(Video below shows the implementation of functionalities as mentioned above)
(Tested against the bun run dev Input->Editor Demo in packages/examples/)

output.mp4

[Copilot]

Pull request overview

Adds multi-click mouse selection support for edit-buffer-backed renderables (e.g., Textarea) so double-click selects the clicked word and triple-click selects the clicked line, with regression tests covering the new selection behaviors.

Changes:

• Track consecutive clicks in CliRenderer and intercept double-/triple-clicks for EditBufferRenderable before the normal drag-selection path.
• Implement word-token and line selection helpers on EditBufferRenderable.
• Add selection regression tests for double-click word selection and triple-click line selection (plus boundary cases).

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
packages/core/src/renderer.ts	Adds click-sequence tracking and dispatches edit-buffer multi-click selection actions.
packages/core/src/renderables/EditBufferRenderable.ts	Implements selectWordAt / selectLineAt and supporting word-token detection.
packages/core/src/renderables/tests/Textarea.selection.test.ts	Adds regression tests for new multi-click selection behaviors and edge cases.

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[Karvy-Singh]

Hello @simonklee and @kommander,

Have you had a chance to review the code for the feature ?
Please suggest any changes you see fit and require from my side.

(P.S. Thank you for running the checks earlier, ever since I have only merged the latest change done for updating Node version in my existing PR.)