refactor: hexagonal architecture remediation — IDP adapter selection

[ancongui]

Summary

• IDP Core: Created IdpProperties with firefly.idp.provider discriminator, IdpWebAutoConfiguration with @ConditionalOnBean(IdpAdapter.class), and moved IdpController to core
• Keycloak: Rewrote KeycloakAutoConfiguration with @ConditionalOnProperty(firefly.idp.provider=keycloak) + @ConditionalOnClass(Keycloak.class), removed stereotype annotations from 6 classes, folded CorsConfig
• Cognito: Rewrote CognitoConfiguration as @AutoConfiguration, removed @ComponentScan, standardized prefix to firefly.idp.cognito, created .imports file
• Internal-DB: Rewrote InternalDbIdpConfiguration as @AutoConfiguration, removed @ComponentScan, standardized prefix to firefly.idp.internal-db, created .imports file
• All adapters now activate purely via application.yml — no POM changes needed to switch providers

Architecture Pattern

Each adapter follows the reference pattern:

@AutoConfiguration
@ConditionalOnClass(ProviderSDK.class)
@ConditionalOnProperty(name = "firefly.idp.provider", havingValue = "keycloak")
@EnableConfigurationProperties(ProviderProperties.class)
public class ProviderAutoConfiguration {
    @Bean @ConditionalOnMissingBean
    public IdpAdapter idpAdapter(...) { ... }
}

Configuration

firefly:
  idp:
    provider: keycloak  # or cognito, internal-db
    keycloak:
      server-url: https://...
      realm: myrealm

Test Plan

• All 4 modules compile successfully
• Start application with firefly.idp.provider=keycloak — verify only Keycloak beans load
• Start with firefly.idp.provider=cognito — verify only Cognito beans load
• Start with no provider set — verify no IDP beans load
• Verify @ConditionalOnMissingBean allows bean overrides