Reorganize worker entry layer into worker/entry/ (M8 part 1/3)

Pulls the worker process entry point, parent<->worker IPC plumbing, message validation schema, and crash-recovery handler into a single src/main/worker/entry/ module. No runtime behavior changes — only directory + file-name renames plus import-path updates: worker-entry.ts -> entry/index.ts, worker-message-handler.ts -> entry/message-handler.ts, worker-rpc.ts -> entry/rpc.ts, worker-crash-recovery.ts -> entry/crash-recovery.ts, worker-types.ts -> entry/types.ts. electron.vite.config.ts, worker-service.ts, handlers/*.ts, pi-agent-factory.ts, and worker-runner.ts updated to point at the new locations.

src/main/worker/handlers/handler-context.ts

@@ -1,5 +1,5 @@
 import type { z } from "zod";
-import type { WorkerServiceDependencies, workerMessageSchema } from "../worker-types";
+import type { WorkerServiceDependencies, workerMessageSchema } from "../entry/types";
 
 export type WorkerMessageEvent = z.infer<typeof workerMessageSchema>;
 

src/main/worker/handlers/run-finished-helpers.ts

@@ -2,7 +2,7 @@ import type { z } from "zod";
 import { createCircuitBreaker } from "../circuit-breaker";
 import { handleFailureEscalation, handleSuccessReset } from "../failure-escalation";
 import { persistRunEvent } from "../run-event-recorder";
-import type { workerMessageSchema } from "../worker-types";
+import type { workerMessageSchema } from "../entry/types";
 import type { HandlerContext, HandlerDeps, WorkerMessageEvent } from "./handler-context";
 
 type RunFinishedEvent = Extract<WorkerMessageEvent, { type: "run-finished" }>;