feat: add OIDC tables and update federation cache for improved token management

migrations/011_oidc_rp_foundation.sql

@@ -67,16 +67,19 @@ CREATE TABLE IF NOT EXISTS oidc_federation_cache (
     issuer VARCHAR(255) NOT NULL,
     subject VARCHAR(255) NULL,
     fetch_url VARCHAR(500) NOT NULL,
+    cache_key BINARY(32) GENERATED ALWAYS AS (
+        UNHEX(
+            SHA2(
+                JSON_ARRAY(document_type, issuer, subject, fetch_url),
+                256
+            )
+        )
+    ) STORED,
     payload_json JSON NOT NULL,
     expires_at DATETIME NOT NULL,
     created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
     updated_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
-    UNIQUE KEY oidc_federation_cache_unique (
-        document_type,
-        issuer,
-        subject,
-        fetch_url
-    ),
+    UNIQUE KEY oidc_federation_cache_unique (cache_key),
     KEY oidc_federation_cache_expires_idx (expires_at)
 );