feat: add agent search config and system assistant defaults

Adds a config jsonb column to agents for per-agent search settings
(enabled, rerank, maxResults). Types systemAssistants with rename and
rerank sub-objects. Backfills missing systemAssistants keys on settings
fetch. Includes generated drizzle migrations.

server/api/agent/[id]/index.patch.ts

@@ -15,6 +15,13 @@ export default defineEventHandler(async (event) => {
                 systemPrompt: z.string().nullable().optional(),
                 imageUrl: z.string().optional(),
                 defaultModelId: z.string().optional(),
+                config: z.object({
+                    search: z.object({
+                        enabled: z.boolean(),
+                        rerank: z.boolean(),
+                        maxResults: z.number().min(1).max(50),
+                    }).optional(),
+                }).optional(),
             })
             .safeParse(body),
     );
@@ -28,15 +35,17 @@ export default defineEventHandler(async (event) => {
 
     const agentId = getRouterParam(event, 'id')!;
 
-    const { name, systemPrompt, imageUrl, defaultModelId } = result.data;
+    const { name, systemPrompt, imageUrl, defaultModelId, config } = result.data;
+
+    const updateData: Record<string, any> = {};
+    if (name !== undefined) updateData.name = name;
+    if (systemPrompt !== undefined) updateData.systemPrompt = systemPrompt;
+    if (imageUrl !== undefined) updateData.imageUrl = imageUrl;
+    if (defaultModelId !== undefined) updateData.defaultModelId = defaultModelId;
+    if (config !== undefined) updateData.config = config;
 
     const res = await db.update(agents)
-        .set({
-            name,
-            systemPrompt,
-            imageUrl,
-            defaultModelId,
-        })
+        .set(updateData)
         .where(
             and(
                 eq(agents.id, agentId),
@@ -55,10 +64,7 @@ export default defineEventHandler(async (event) => {
         op: 'update',
         payload: {
             id: agentId,
-            name,
-            systemPrompt,
-            imageUrl,
-            defaultModelId,
+            ...updateData,
         },
     });