refactor(core): split index.ts and config-handler.ts into focused modules

Main entry point:
- create-hooks.ts, create-tools.ts, create-managers.ts
- plugin-interface.ts: plugin interface types
- plugin/ directory: plugin lifecycle modules

Config handler:
- agent-config-handler.ts, command-config-handler.ts
- tool-config-handler.ts, mcp-config-handler.ts
- provider-config-handler.ts, category-config-resolver.ts
- agent-priority-order.ts, prometheus-agent-config-builder.ts
- plugin-components-loader.ts

src/plugin/available-categories.ts

@@ -0,0 +1,29 @@
+import type { AvailableCategory } from "../agents/dynamic-agent-prompt-builder"
+import type { OhMyOpenCodeConfig } from "../config"
+
+import {
+  CATEGORY_DESCRIPTIONS,
+  DEFAULT_CATEGORIES,
+} from "../tools/delegate-task/constants"
+
+export function createAvailableCategories(
+  pluginConfig: OhMyOpenCodeConfig,
+): AvailableCategory[] {
+  const mergedCategories = pluginConfig.categories
+    ? { ...DEFAULT_CATEGORIES, ...pluginConfig.categories }
+    : DEFAULT_CATEGORIES
+
+  return Object.entries(mergedCategories).map(([name, categoryConfig]) => {
+    const model =
+      typeof categoryConfig.model === "string" ? categoryConfig.model : undefined
+
+    return {
+      name,
+      description:
+        pluginConfig.categories?.[name]?.description ??
+        CATEGORY_DESCRIPTIONS[name] ??
+        "General tasks",
+      model,
+    }
+  })
+}