fix: color single security scheme

[adjsky]

Problem
Currently, if securitySchemes is defined with a single scheme, uncolored security scheme will be displayed in the API client.

Before:

After:

Explanation
The issue is... the needed styles weren't applied to text if a single scheme is provided.

Solution
Put .security-scheme-selector span into a separate class, and use it for scheme labels.

[changeset-bot]

🦋 Changeset detected

Latest commit: 9c2147a

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 13 packages

Name	Type
@scalar/api-client	Patch
@scalar/api-client-react	Patch
@scalar/api-reference	Patch
@scalar/play-button	Patch
@scalar/api-reference-react	Patch
@scalar/cli	Patch
@scalar/express-api-reference	Patch
@scalar/fastify-api-reference	Patch
@scalar/hono-api-reference	Patch
@scalar/nestjs-api-reference	Patch
@scalar/nextjs-api-reference	Patch
@scalar/nuxt	Patch
@scalar/docusaurus	Patch

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[adjsky]

Oh... after opening PR I noticed that CollapsibleSection adds extra styles to any span inside options. Plans changed, so I abandoned the previous solution, and decided to put .security-scheme-selector span into a separate class, and use it for labels.

[marclave]

nice work @adjsky !!