Fix TSX Badge URL Extraction in ExportPanel - #8907

Description

Fixes badge download failures in ExportPanel.tsx when the export format is set to TSX by improving badge URL extraction to support all supported snippet formats.

Changes

• Updated badge URL extraction logic to correctly handle TSX export snippets.
• Extended parsing to support URLs embedded in JavaScript template literals in addition to the existing Markdown and HTML formats.
• Ensured download actions (SVG, PNG, and PDF) use the extracted badge URL regardless of the selected export format.
• Preserved existing behavior for Markdown and HTML snippets.
• Added regression tests covering all supported export formats.

Validation

Implemented tests covering:

• Successful URL extraction from Markdown snippets.
• Successful URL extraction from HTML snippets.
• Successful URL extraction from TSX template literal snippets.
• SVG, PNG, and PDF downloads using the extracted URL.
• Invalid or malformed snippets continuing to return an appropriate error instead of failing unexpectedly.

Verification

✅ vitest run passes successfully.
✅ Badge downloads work correctly for Markdown, HTML, and TSX export formats.
✅ Existing download functionality remains unchanged for previously supported formats.

Fixes #8769

Pillar

• 🎨 Pillar 1 — New Theme Design
• 📐 Pillar 2 — Geometric SVG Improvement
• 🕐 Pillar 3 — Timezone Logic Optimization
• 🛠️ Other (Bug fix, refactoring, docs)

Visual Preview

Can Check in the Files Changed Section.

Checklist before requesting a review:

• I have read the CONTRIBUTING.md file.
• I have tested these changes locally (localhost:3000/api/streak?user=YOUR_USERNAME).
• I have run npm run format and npm run lint locally and resolved all errors (CI will fail otherwise).
• My commits follow the Conventional Commits format (e.g., feat(themes): ..., fix(calculate): ...).
• I have updated README.md if I added a new theme or URL parameter.
• I have started the repo.
• I have made sure that i have only one commit to merge in this PR.
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