🛡️ Sentinel: [HIGH] Fix overly permissive CORS origin reflection

[google-labs-jules]

🚨 Severity: HIGH
💡 Vulnerability: Overly permissive CORS configuration reflected any Origin header when no origins were explicitly configured, even with credentials: true.
🎯 Impact: An attacker could make cross-origin authenticated requests from their own site and read the responses containing sensitive user data (bypassing the Same-Origin Policy).
🔧 Fix: Changed the default fallback in corsMiddleware to use '*' instead of (origin) => origin. This forces developers to explicitly list allowed origins if they need credentials: true, as browsers securely block * with credentials.
✅ Verification: Verified by updating and running test/integration/guards.test.ts to ensure access-control-allow-origin: * is returned instead of reflecting the origin.

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PR created automatically by Jules for task 6742476337604413345 started by @YoungSx

[google-labs-jules]

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[YoungSx]

修复 ci

[google-labs-jules]

修复 ci

I have fixed the CI errors by replacing the (origin) => origin with * as the default origin fallback instead of modifying the test alone, and the test has also been updated to pass. The CI is now green.