feat: Fix onboarding tooltip positioning, auto-skip, and measurement stability under GSSoC'26

[janmejay1438]

Description

Fixes onboarding tour positioning and measurement issues in OnboardingTour.tsx.

Changes made

Fixed tooltip overflowing outside the viewport on certain steps
Removed onboarding auto-skip behavior when target measurement temporarily fails
Improved target measurement stability by replacing timeout-based measurement with double requestAnimationFrame
Stabilized onboarding positioning during auto-scroll transitions
Preserved keyboard navigation and resize re-measure support

Related Issue

Closes #922

Type of Contribution

• Bug fix
• GSSoC contribution

Participant Info

• GitHub username: @janmejay1438
• Contribution level (Intermediate):

Screen Recording

Onboarding.mp4

Checklist

• I have read the contribution guidelines
• My changes follow the project structure
• I have tested my changes in Chrome, Firefox, and Safari
• bun run lint passes (no ESLint errors)
• bunx tsc --noEmit passes (no TypeScript errors)
• New interactive elements have aria-label / accessible names
• No console.log statements left in
• This PR is related to a valid issue
• Screen recording attached above (required for UI/feature/design changes)

[vercel]

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[github-actions]

✅ PR Format Check Passed — @janmejay1438

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[github-actions]

👋 Thanks for your PR, @janmejay1438!

Welcome to Reframe — a browser-based video editor built for everyone 🎬

🟠 GSSoC'26 PR detected — thanks for contributing under GirlScript Summer of Code 2026!

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Quick checklist

• PR title follows Conventional Commits (e.g. feat: add dark mode)
• Linked the issue this PR closes (e.g. Closes #123)
• Tested the changes locally (bun run dev)
• Build passes (bun run build)

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