feat(ultrawork): implement per-message model override with deferred DB retry strategy

- Add per-message ultrawork mode detection via keyword matching
- Implement deferred DB override strategy using microtask retry loop
- Fall back to setTimeout after 10 microtask retries for robustness
- Update agent configuration schema with ultrawork model/variant fields
- Integrate with chat.message hook to apply overrides on detection
- Add comprehensive tests for all override scenarios
- Generated schema includes ultrawork configuration

🤖 Generated with assistance of OhMyOpenCode (https://github.com/code-yeongyu/oh-my-opencode)

src/config/schema/agent-overrides.ts

@@ -38,6 +38,13 @@ export const AgentOverrideConfigSchema = z.object({
   textVerbosity: z.enum(["low", "medium", "high"]).optional(),
   /** Provider-specific options. Passed directly to OpenCode SDK. */
   providerOptions: z.record(z.string(), z.unknown()).optional(),
+  /** Per-message ultrawork override model/variant when ultrawork keyword is detected. */
+  ultrawork: z
+    .object({
+      model: z.string().optional(),
+      variant: z.string().optional(),
+    })
+    .optional(),
 })
 
 export const AgentOverridesSchema = z.object({