feat(appcheck): appcheck recaptcha enterprise support

[cynthiajoan]

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[gemini-code-assist]

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[cynthiajoan]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces support for reCAPTCHA providers across Android, iOS, and Web platforms in firebase_app_check and integrates recaptchaSiteKey into FirebaseOptions across firebase_core platforms. Key feedback includes removing mavenLocal() from build files to prevent consumer dependency issues, adhering to the repository style guide by avoiding the ! operator in _safeToDart, and exporting WebProvider to replace dynamic types with safer, strongly-typed declarations in the example app.

[gemini-code-assist]

Avoid adding mavenLocal() to the library's repositories as it can cause dependency resolution issues and slow down builds for consumers of the plugin. This is typically used only for local development and should be removed before merging.

    google()
    mavenCentral()

[gemini-code-assist]

Avoid adding mavenLocal() to the library's repositories as it can cause dependency resolution issues and slow down builds for consumers of the plugin. This is typically used only for local development and should be removed before merging.

    google()
    mavenCentral()

[gemini-code-assist]

The use of the ! operator violates the repository style guide (Rule 23: "NO ! operator. Use ? and flow analysis"). We can safely promote jsString to a non-nullable type by checking jsString == null first, which allows calling toDart without the ! operator.

Suggested change

	String? _safeToDart(JSString? jsString) {
	if (jsString.isUndefinedOrNull) return null;
	return jsString!.toDart;
	}
	String? _safeToDart(JSString? jsString) {
	if (jsString == null || jsString.isUndefinedOrNull) return null;
	return jsString.toDart;
	}

References

1. Null Safety: NO ! operator. Use ? and flow analysis (e.g. if (x != null)). ^(link)

[gemini-code-assist]

Export WebProvider from the platform interface so that consumers can use it as a type in their code, ensuring consistency with other platform providers like AndroidAppCheckProvider and AppleAppCheckProvider.

Suggested change

	WebDebugProvider,
	WebReCaptchaProvider,
	WebDebugProvider,
	WebProvider,
	WebReCaptchaProvider,

[gemini-code-assist]

Since WebProvider is now exported, we can use WebProvider? instead of dynamic for providerWeb to improve type safety.

Suggested change

	dynamic providerWeb;
	WebProvider? providerWeb;