feat(harbor-manager): implemented arm orchestration and vite dev harness

- Introduced `resolveArmLaunch` to inherit dataset, task samples, and configurations from existing experiment arms for consistent comparisons.
- Added a POST `/api/experiments/:id/arms` endpoint to programmatically launch new arms within an experiment.
- Created `scripts/dev.ts` and `vite.config.ts` to provide a unified development environment with React Fast Refresh and API proxying.
- Integrated an "Add Arm" UI component in the dashboard to allow user-driven experimental variants.
- Configured Vite to proxy requests to the Bun API server, improving iteration speed during dashboard development.

package.json

@@ -105,6 +105,7 @@
     "collab:relay": "bun --cwd=packages/collab-web run relay",
     "collab:mock-host": "bun --cwd=packages/collab-web run mock-host",
     "collab:web:build": "bun --cwd=packages/collab-web run build",
+    "hmgr": "bun --cwd=packages/harbor-manager run dev",
     "claude:trace": "bun scripts/claude-trace.ts",
     "build": "bun run --workspaces --if-present build",
     "build:native": "bun --cwd=packages/natives run build",