test(generator): add coverage for exact SVG dimensions per size parameter

[Subhooo5]

Description

Fixes #723

• Added focused generator test coverage to verify exact SVG width and height values for small, medium, and large size presets.
• Removed the unused escapeXML import from app/api/streak/route.ts to resolve the npm run lint warning and keep the CI/lint pipeline clean.

Pillar

• 🛠️ Other (Bug fix, refactoring, docs)

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.
• My commits follow the Conventional Commits format.
• I have starred the repo.
• I have made sure that i have only one commit to merge in this PR.
• The SVG output matches the CommitPulse "premium quality" aesthetic standard.

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[Subhooo5]

Hey @JhaSourav07 Desired test successfully added. All existing tests pass locally. Feel free to review, add necessary labels and merge it. 🫂🚀

[Aamod007]

@Subhooo5 Two clean changes: removes unused escapeXML import (lint fix), adds 3 dimension tests verifying exact SVG sizes for small/medium/large