fix(share): replace btoa/atob with encodeURIComponent for Unicode support

[Tarulatapriya]

Fix Summary

Fixes an issue where sharing video recipes with text overlays containing Unicode characters (e.g., emojis 🎬 😊, non-Latin text) caused an unhandled DOMException / InvalidCharacterError in JavaScript's native btoa() method:

Failed to execute 'btoa' on 'Window': The string to be encoded contains characters outside of the Latin1 range.

Changes Made

• URL Recipe Encoding: Replaced btoa() / atob() with encodeURIComponent(JSON.stringify(recipe)) and decodeURIComponent(encoded) for settings query parameters.
• Backward Compatibility: Added a decodeURIComponent(escape(atob(encoded))) fallback in decodeRecipe() to support decoding legacy base64-encoded share URLs seamlessly.
• Unit Tests: Added automated unit tests in src/hooks/tests/useVideoEditor.test.ts to verify Unicode text overlay handling.
• Validation: All 129 vitest unit tests across 14 test suites pass cleanly.

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[github-actions]

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[github-actions]

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