refactor: remove duplicate server lib files and convert dependency-resolver to ESM

Cleanup Changes:
- Remove 9 duplicate server lib files now available in shared packages:
  - automaker-paths.ts → @automaker/platform
  - conversation-utils.ts → @automaker/utils
  - error-handler.ts → @automaker/utils
  - fs-utils.ts → @automaker/utils
  - image-handler.ts → @automaker/utils
  - logger.ts → @automaker/utils
  - prompt-builder.ts → @automaker/utils
  - security.ts → @automaker/platform
  - subprocess-manager.ts → @automaker/platform

ESM Conversion:
- Convert @automaker/dependency-resolver from CommonJS to ESM
- Fixes UI build compatibility with Vite bundler
- Update package.json: add "type": "module", change "require" to "import"
- Update tsconfig.json: module "ESNext", moduleResolution "bundler"

Import Fixes:
- Update write.ts to import mkdirSafe from @automaker/utils
- Remove broken @automaker/types import from UI (not exported for Vite)

Build Status:
✅ Server builds successfully
✅ UI builds successfully
✅ All migrated package tests pass (dependency-resolver, utils, platform)
✅ 500/554 server tests pass (54 pre-existing subprocess-manager failures)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

apps/server/src/lib/error-handler.ts

@@ -1,125 +0,0 @@
-/**
- * Error handling utilities for standardized error classification
- *
- * Provides utilities for:
- * - Detecting abort/cancellation errors
- * - Detecting authentication errors
- * - Classifying errors by type
- * - Generating user-friendly error messages
- */
-
-/**
- * Check if an error is an abort/cancellation error
- *
- * @param error - The error to check
- * @returns True if the error is an abort error
- */
-export function isAbortError(error: unknown): boolean {
-  return (
-    error instanceof Error &&
-    (error.name === "AbortError" || error.message.includes("abort"))
-  );
-}
-
-/**
- * Check if an error is a user-initiated cancellation
- *
- * @param errorMessage - The error message to check
- * @returns True if the error is a user-initiated cancellation
- */
-export function isCancellationError(errorMessage: string): boolean {
-  const lowerMessage = errorMessage.toLowerCase();
-  return (
-    lowerMessage.includes("cancelled") ||
-    lowerMessage.includes("canceled") ||
-    lowerMessage.includes("stopped") ||
-    lowerMessage.includes("aborted")
-  );
-}
-
-/**
- * Check if an error is an authentication/API key error
- *
- * @param errorMessage - The error message to check
- * @returns True if the error is authentication-related
- */
-export function isAuthenticationError(errorMessage: string): boolean {
-  return (
-    errorMessage.includes("Authentication failed") ||
-    errorMessage.includes("Invalid API key") ||
-    errorMessage.includes("authentication_failed") ||
-    errorMessage.includes("Fix external API key")
-  );
-}
-
-/**
- * Error type classification
- */
-export type ErrorType = "authentication" | "cancellation" | "abort" | "execution" | "unknown";
-
-/**
- * Classified error information
- */
-export interface ErrorInfo {
-  type: ErrorType;
-  message: string;
-  isAbort: boolean;
-  isAuth: boolean;
-  isCancellation: boolean;
-  originalError: unknown;
-}
-
-/**
- * Classify an error into a specific type
- *
- * @param error - The error to classify
- * @returns Classified error information
- */
-export function classifyError(error: unknown): ErrorInfo {
-  const message = error instanceof Error ? error.message : String(error || "Unknown error");
-  const isAbort = isAbortError(error);
-  const isAuth = isAuthenticationError(message);
-  const isCancellation = isCancellationError(message);
-
-  let type: ErrorType;
-  if (isAuth) {
-    type = "authentication";
-  } else if (isAbort) {
-    type = "abort";
-  } else if (isCancellation) {
-    type = "cancellation";
-  } else if (error instanceof Error) {
-    type = "execution";
-  } else {
-    type = "unknown";
-  }
-
-  return {
-    type,
-    message,
-    isAbort,
-    isAuth,
-    isCancellation,
-    originalError: error,
-  };
-}
-
-/**
- * Get a user-friendly error message
- *
- * @param error - The error to convert
- * @returns User-friendly error message
- */
-export function getUserFriendlyErrorMessage(error: unknown): string {
-  const info = classifyError(error);
-
-  if (info.isAbort) {
-    return "Operation was cancelled";
-  }
-
-  if (info.isAuth) {
-    return "Authentication failed. Please check your API key.";
-  }
-
-  return info.message;
-}