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-interface.ts

@@ -0,0 +1,65 @@
+import type { PluginContext, PluginInterface, ToolsRecord } from "./plugin/types"
+import type { OhMyOpenCodeConfig } from "./config"
+
+import { createChatParamsHandler } from "./plugin/chat-params"
+import { createChatMessageHandler } from "./plugin/chat-message"
+import { createMessagesTransformHandler } from "./plugin/messages-transform"
+import { createEventHandler } from "./plugin/event"
+import { createToolExecuteAfterHandler } from "./plugin/tool-execute-after"
+import { createToolExecuteBeforeHandler } from "./plugin/tool-execute-before"
+
+import type { CreatedHooks } from "./create-hooks"
+import type { Managers } from "./create-managers"
+
+export function createPluginInterface(args: {
+  ctx: PluginContext
+  pluginConfig: OhMyOpenCodeConfig
+  firstMessageVariantGate: {
+    shouldOverride: (sessionID: string) => boolean
+    markApplied: (sessionID: string) => void
+    markSessionCreated: (sessionInfo: { id?: string; title?: string; parentID?: string } | undefined) => void
+    clear: (sessionID: string) => void
+  }
+  managers: Managers
+  hooks: CreatedHooks
+  tools: ToolsRecord
+}): PluginInterface {
+  const { ctx, pluginConfig, firstMessageVariantGate, managers, hooks, tools } =
+    args
+
+  return {
+    tool: tools,
+
+    "chat.params": createChatParamsHandler({ anthropicEffort: hooks.anthropicEffort }),
+
+    "chat.message": createChatMessageHandler({
+      ctx,
+      pluginConfig,
+      firstMessageVariantGate,
+      hooks,
+    }),
+
+    "experimental.chat.messages.transform": createMessagesTransformHandler({
+      hooks,
+    }),
+
+    config: managers.configHandler,
+
+    event: createEventHandler({
+      ctx,
+      pluginConfig,
+      firstMessageVariantGate,
+      managers,
+      hooks,
+    }),
+
+    "tool.execute.before": createToolExecuteBeforeHandler({
+      ctx,
+      hooks,
+    }),
+
+    "tool.execute.after": createToolExecuteAfterHandler({
+      hooks,
+    }),
+  }
+}