feat(server): basic context api (#10056)

fix CLOUD-97
fix CLOUD-98

packages/backend/server/migrations/20250210083416_ai_context/migration.sql

@@ -0,0 +1,13 @@
+-- CreateTable
+CREATE TABLE "ai_contexts" (
+    "id" VARCHAR NOT NULL,
+    "session_id" VARCHAR NOT NULL,
+    "config" JSON NOT NULL,
+    "created_at" TIMESTAMPTZ(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updated_at" TIMESTAMPTZ(3) NOT NULL,
+
+    CONSTRAINT "ai_contexts_pkey" PRIMARY KEY ("id")
+);
+
+-- AddForeignKey
+ALTER TABLE "ai_contexts" ADD CONSTRAINT "ai_contexts_session_id_fkey" FOREIGN KEY ("session_id") REFERENCES "ai_sessions_metadata"("id") ON DELETE CASCADE ON UPDATE CASCADE;