test : added unit tests for og-user-params helpers

[tmdeveloper007]

Closes #2459.

Summary of What Has Been Done:
Added a dedicated vitest test file test/og-user-params.test.ts that pins the behaviour of every pure helper in src/lib/og-user-params.ts. The tests are deterministic (no network, no Date.now) and use the same describe/it/expect style as the rest of the suite.

Changes Made:

• New file: test/og-user-params.test.ts (14 tests, all passing under npm test).
• Coverage for the public normalizeOgUserParams(searchParams: URLSearchParams) export, including:
  • The happy path (all inputs supplied, expected avatar URL composition).
  • Missing or invalid username falling back to "developer".
  • name falling back to username when missing.
  • topLang falling back to "JavaScript" when missing.
  • name and topLang truncating at the MAX_NAME_LENGTH (48) and MAX_LANGUAGE_LENGTH (24) caps.
  • streak and commits returning 0 for empty / non-numeric / negative inputs.
  • streak and commits flooring decimal values.
  • streak and commits clamping at MAX_METRIC_VALUE (999999) and accepting the boundary value 999999.

Impact it Made:
Locks the contract for the public OG user-card query-param normaliser used by the /api/og/user route. Future refactors of the avatar URL composition, the fallback chain, or the metric clamping will surface a test failure rather than a silent UI regression. No production code was modified; the change is limited to one new test file.

[github-actions]

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