refactor(delegate-task): deduplicate DelegatedModelConfig + registry refactor

- Move DelegatedModelConfig to src/shared/model-resolution-types.ts
- Re-export from delegate-task/types.ts (preserving import paths)
- Replace background-agent/types.ts local duplicate with shared import
- Consolidate model-settings-compatibility.ts registry patterns

src/tools/delegate-task/tools.ts

@@ -1,5 +1,5 @@
 import { tool, type ToolDefinition } from "@opencode-ai/plugin"
-import type { DelegateTaskArgs, ToolContextWithMetadata, DelegateTaskToolOptions } from "./types"
+import type { DelegateTaskArgs, DelegatedModelConfig, ToolContextWithMetadata, DelegateTaskToolOptions } from "./types"
 import { CATEGORY_DESCRIPTIONS } from "./constants"
 import { SISYPHUS_JUNIOR_AGENT } from "./sisyphus-junior-agent"
 import { mergeCategories } from "../../shared/merge-categories"
@@ -178,18 +178,7 @@ export function createDelegateTask(options: DelegateTaskToolOptions): ToolDefini
         : undefined
 
       let agentToUse: string
-      let categoryModel:
-        | {
-            providerID: string
-            modelID: string
-            variant?: string
-            reasoningEffort?: string
-            temperature?: number
-            top_p?: number
-            maxTokens?: number
-            thinking?: { type: "enabled" | "disabled"; budgetTokens?: number }
-          }
-        | undefined
+      let categoryModel: DelegatedModelConfig | undefined
       let categoryPromptAppend: string | undefined
       let modelInfo: import("../../features/task-toast-manager/types").ModelFallbackInfo | undefined
       let actualModel: string | undefined

src/tools/delegate-task/types.ts

@@ -71,16 +71,8 @@ export interface DelegateTaskToolOptions {
   syncPollTimeoutMs?: number
 }
 
-export interface DelegatedModelConfig {
-  providerID: string
-  modelID: string
-  variant?: string
-  reasoningEffort?: string
-  temperature?: number
-  top_p?: number
-  maxTokens?: number
-  thinking?: { type: "enabled" | "disabled"; budgetTokens?: number }
-}
+import type { DelegatedModelConfig } from "../../shared/model-resolution-types"
+export type { DelegatedModelConfig }
 
 export interface BuildSystemContentInput {
   skillContent?: string