fix: add .int() to runTimeoutSeconds zod schema for consistency

Matches convention used by all other *Seconds/*Ms timeout fields.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/config/zod-schema.agent-defaults.ts

@@ -146,7 +146,7 @@ export const AgentDefaultsSchema = z
         archiveAfterMinutes: z.number().int().positive().optional(),
         model: AgentModelSchema.optional(),
         thinking: z.string().optional(),
-        runTimeoutSeconds: z.number().min(0).optional(),
+        runTimeoutSeconds: z.number().int().min(0).optional(),
         announceTimeoutMs: z.number().int().positive().optional(),
       })
       .strict()