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/ui/src/lib/agent-context-parser.ts

@@ -3,8 +3,6 @@
  * Extracts useful information from agent context files for display in kanban cards
  */
 
-import { DEFAULT_MODELS } from "@automaker/types";
-
 export interface AgentTaskInfo {
   // Task list extracted from TodoWrite tool calls
   todos: {
@@ -29,7 +27,7 @@ export interface AgentTaskInfo {
 /**
  * Default model used by the feature executor
  */
-export const DEFAULT_MODEL = DEFAULT_MODELS.claude;
+export const DEFAULT_MODEL = "claude-opus-4-5-20251101";
 
 /**
  * Formats a model name for display