fix: reduce PHPStan baseline errors by 42%

[Spomky]

Summary

• Add precise array{} shape type annotations to Symfony DI extension and security factory methods, eliminating ~65 baseline entries
• Fix type mismatches in AuthenticationExtensions (remove incompatible @readonly, fix offsetGet return type)
• Fix PublicKeyCredentialRequestOptions phpdoc typo (AuthenticationExtensions → AuthenticationExtension)
• Add typed return phpdoc to TPMAttestationStatementSupport::checkCertInfo() and extract getRsaParameters() method
• Remove redundant type checks in options factories (is_int, is_string on already-typed values)
• Fix realpath() return handling in WebauthnBundle

Reduces PHPStan baseline from 154 to 90 entries (-42%) while keeping all 275 tests passing.

Test plan

• castor phpunit — all 275 tests pass
• castor phpstan — passes with updated baseline
• CI pipeline validates all checks

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