Add runtime provider controls and searchable AI routing

Manage provider keys at runtime, route current-information questions through server-side search with safe fallback, and scope OOBE usage claims to grants.

src/main/kotlin/com/osglab/account/features/oobe/OobeModels.kt

@@ -103,6 +103,7 @@ sealed interface OobeRefreshRotationResult {
 
 data class OobeRequestClaim(
     val subjectId: String,
+    val grantId: String,
     val feature: OobeFeature,
     val requestId: String,
 )