fix: resolve 4 bugs in termui

[saurabhhhcodes]

Description

This PR fixes real bugs found in the codebase:

• Added Number.EPSILON to Math.round: prevents floating-point drift (e.g. 1.005 * 100 rounding to 100 instead of 101).
• Added explicit radix to parseInt: without 10, strings like '0x1F' or '08' parse in unintended bases.
• Removed redundant boolean comparison: x === true is equivalent to x (and x === false to !x), and shorter to read.
• Replaced global isNaN with Number.isNaN: the global version coerces its argument, so isNaN('1') returns false while Number.isNaN is strict.

Type of Change

• Bug fix (non-breaking change fixing an issue)

How Has This Been Tested?

• Local manual testing

Checklist

• My code follows the style guidelines
• I have performed a self-review

Related Issue

Ref: #3461

Summary by CodeRabbit

• Bug Fixes
  • Improved progress percentage rounding for more accurate displayed values.
  • Improved keyboard tab selection handling in the widget gallery.
  • Strengthened validation of numeric choices in selection prompts.

[coderabbitai]

📝 Walkthrough

Walkthrough

The changes improve numeric handling in the Pomodoro progress label, widget gallery tab selection, and UI prompt selection validation.

Changes

Numeric correctness corrections

Layer / File(s)	Summary
Progress percentage rounding examples/pomodoro-timer/src/index.tsx	The progress label adds Number.EPSILON before rounding the percentage.
Tab-key parsing examples/widget-gallery/src/index.ts	Tab keys are parsed with an explicit decimal radix.
Prompt selection validation packages/ui/src/prompts.ts	promptSelect uses Number.isNaN to validate parsed selections.

Estimated code review effort: 2 (Simple) | ~10 minutes

Possibly related PRs

• Karanjot786/TermUI#3413: Overlaps with the Pomodoro percentage and widget gallery parsing changes.
• Karanjot786/TermUI#3418: Applies the same Number.isNaN change in promptSelect.
• Karanjot786/TermUI#3426: Overlaps with the widget gallery parsing and prompt validation changes.

Suggested reviewers: karanjot786

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description explains the fixes but omits required package, GSSoC, and template checklist details, and does not use the required issue-closing syntax.	Add the package list, complete the required checklist and GSSoC section, and change the issue reference to Closes #3461``.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies a bug-fix pull request that resolves four TermUI bugs.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@examples/pomodoro-timer/src/index.tsx`:
- Line 185: Update the label calculation in the relevant timer rendering method
so the epsilon is added to this._value before multiplying by 100, ensuring
boundary values round correctly; retain the existing conditional label behavior
and add a regression test covering a value such as 0.145 that must display 15%.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: deee3ef8-9498-4d84-859c-32903b46f127

📥 Commits

Reviewing files that changed from the base of the PR and between 6c7584e and 4cad94e.

📒 Files selected for processing (3)

• examples/pomodoro-timer/src/index.tsx
• examples/widget-gallery/src/index.ts
• packages/ui/src/prompts.ts

[coderabbitai]

🎯 Functional Correctness | 🟡 Minor | ⚡ Quick win

Apply the epsilon before scaling.

Number.EPSILON is too small after this._value * 100. For example, 0.145 * 100 can produce 14.499999999999998, and adding Number.EPSILON does not reliably move it to 14.5. The label can still display 14% instead of 15%.

Use a scale-aware expression and add a boundary regression test.

Proposed fix

-        const label = this._showLabel ? ` ${Math.round(this._value * 100 + Number.EPSILON)}%` : '';
+        const label = this._showLabel ? ` ${Math.round((this._value + Number.EPSILON) * 100)}%` : '';

📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change

	const label = this._showLabel ? ` ${Math.round(this._value * 100 + Number.EPSILON)}%` : '';
	const label = this._showLabel ? ` ${Math.round((this._value + Number.EPSILON) * 100)}%` : '';

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@examples/pomodoro-timer/src/index.tsx` at line 185, Update the label
calculation in the relevant timer rendering method so the epsilon is added to
this._value before multiplying by 100, ensuring boundary values round correctly;
retain the existing conditional label behavior and add a regression test
covering a value such as 0.145 that must display 15%.