fix(docs): correct View source URLs for acronym-prefixed examples

[Abdeltoto]

Fixes #6296

Checklist

• Includes tests (exampleSourceFileName.test.ts, isReactNodeEmpty(false) in core)
• Update documentation (not required; fixes doc site behavior)

Changes proposed in this pull request

• View source on GitHub: Example export names like HTMLSelectExample were turned into hTMLSelectExample.tsx by lowercasing only the first character. We now derive filenames with lodash/camelCase via a small helper exampleExportNameToSourceFileName, so links resolve to htmlSelectExample.tsx and other acronym-leading names behave consistently.
• Tests: Vitest added to @blueprintjs/docs-app (node environment) for the helper; one extra assertion in utils.test.tsx for isReactNodeEmpty(false).

Reviewers should focus on

• Click View source on GitHub from HTML select docs after deploy; link should hit the real file on develop.
• pnpm --filter @blueprintjs/docs-app test and existing core test suites.

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Description

fix(docs): correct View source URLs for acronym-prefixed examples

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