Add terminal snippets feature with sidebar UI (#377)

* Add terminal snippets feature with sidebar UI

- Add snippets CRUD API endpoints and database schema
- Implement snippets sidebar accessible from TopNavbar
- Add copy to clipboard functionality
- Include tooltips and optimized styling
- Add English and Chinese translations

* Update src/backend/database/routes/snippets.ts

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

---------

Co-authored-by: ZacharyZcR <zacharyzcr1984@gmail.com>
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

src/backend/database/database.ts

@@ -6,6 +6,7 @@ import userRoutes from "./routes/users.js";
 import sshRoutes from "./routes/ssh.js";
 import alertRoutes from "./routes/alerts.js";
 import credentialsRoutes from "./routes/credentials.js";
+import snippetsRoutes from "./routes/snippets.js";
 import cors from "cors";
 import fetch from "node-fetch";
 import fs from "fs";
@@ -30,6 +31,7 @@ import {
   dismissedAlerts,
   sshCredentialUsage,
   settings,
+  snippets,
 } from "./db/schema.js";
 import { getDb } from "./db/index.js";
 import Database from "better-sqlite3";
@@ -1411,6 +1413,7 @@ app.use("/users", userRoutes);
 app.use("/ssh", sshRoutes);
 app.use("/alerts", alertRoutes);
 app.use("/credentials", credentialsRoutes);
+app.use("/snippets", snippetsRoutes);
 
 app.use(
   (