fix: add missing opusContext1mEnabled to SettingsUpdateSchema

The strict Zod schema was rejecting PUT /api/settings because
opusContext1mEnabled was not in the allowlist. This caused all
settings saves to fail server-side with a 400.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: marcfargas

src/web/schemas.ts

@@ -269,6 +269,7 @@ export const SettingsUpdateSchema = z
     tunnelEnabled: z.boolean().optional(),
     tabTwoRows: z.boolean().optional(),
     agentTeamsEnabled: z.boolean().optional(),
+    opusContext1mEnabled: z.boolean().optional(),
     // UI visibility
     showFontControls: z.boolean().optional(),
     showSystemStats: z.boolean().optional(),