feat: add file browser and file download with multi-backend support (#142)

* feat: add file browser and file download with multi-backend support

Adds a built-in File Browser page and a File Download system to Hermes
Web UI, enabling users to browse, edit, preview, upload, and download
files from the workspace directly from the web dashboard.

File Browser (/hermes/files):
- New view FilesView.vue plus components under components/hermes/files/
  (FileTree, FileList, FileBreadcrumb, FileToolbar, FileContextMenu,
  FileEditor, FilePreview, FileRenameModal, FileUploadModal)
- New Pinia store stores/hermes/files.ts for directory tree, selection,
  and editing state
- New API module api/hermes/files.ts
- New server routes routes/hermes/files.ts with CRUD, rename, upload,
  and directory listing
- New service services/hermes/file-provider.ts with a pluggable
  provider architecture (local filesystem + multi-terminal backends)

File Download:
- New server route routes/hermes/download.ts and client API
  api/hermes/download.ts
- Integration in chat messages (MessageItem.vue, MarkdownRenderer.vue)
  to surface downloadable file references

Packaging:
- package.json: add a prepare script so the package can be installed
  directly from a git URL with dist/ built automatically

i18n: add files/download translations to en.ts and zh.ts.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix: use clipboard fallback for non-secure HTTP contexts

navigator.clipboard is undefined on HTTP intranet deployments (only
available in secure contexts). The previous synchronous calls threw
silently and the success toast still fired, making 'copy' actions
appear broken.

- Add packages/client/src/utils/clipboard.ts with execCommand fallback
  via a hidden textarea
- Use the helper in FileContextMenu (copy file path), CodexLoginModal
  (copy user code), NousLoginModal (copy user code), ChatPanel (copy
  session id)
- Each call now awaits the result and shows success/failure based on
  the actual outcome

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

package.json

@@ -50,6 +50,7 @@
     "dev:client": "vite --host",
     "dev:server": "nodemon --signal SIGTERM --watch packages/server/src -e ts,tsx --exec TS_NODE_PROJECT=packages/server/tsconfig.json node -r ts-node/register packages/server/src/index.ts",
     "build": "vue-tsc -b && vite build && tsc --noEmit -p packages/server/tsconfig.json && node scripts/build-server.mjs",
+    "prepare": "[ -d dist ] || npm run build",
     "preview": "vite preview",
     "test": "vitest run",
     "test:watch": "vitest",
@@ -92,6 +93,7 @@
     "koa-send": "^5.0.1",
     "koa-static": "^5.0.0",
     "markdown-it": "^14.1.1",
+    "monaco-editor": "^0.55.1",
     "naive-ui": "^2.44.1",
     "nodemon": "^3.1.14",
     "pinia": "^3.0.4",