Studio: copy the OS-matched update command and keep checkout installs local

The web update banner copied both the macOS/Linux curl and the Windows irm
one-liner joined by a newline, so pasting into a single terminal ran the wrong
shell's command and errored. Detect the OS from navigator.userAgent and copy
only the matching command; the banner still displays both.

In the settings update panel, editable/local_repo checkouts were told to run
the remote curl/irm installer, which is the PyPI path (install.sh only installs
locally with --local) and would replace an editable checkout with a PyPI
package. Use the OS-specific local installer (./install.sh --local /
.\install.ps1 --local) as the checkout update command and drop the now
redundant duplicate block plus its unused localInstallerFallback locale key.

studio/frontend/src/components/web/update-banner.tsx

@@ -10,7 +10,9 @@ import { type ReactElement, useEffect, useRef, useState } from "react";
 
 const STUDIO_UPDATE_UNIX_CMD = "curl -fsSL https://unsloth.ai/install.sh | sh";
 const STUDIO_UPDATE_WINDOWS_CMD = "irm https://unsloth.ai/install.ps1 | iex";
-const STUDIO_UPDATE_COPY_CMD = `${STUDIO_UPDATE_UNIX_CMD}\n${STUDIO_UPDATE_WINDOWS_CMD}`;
+// Match "windows" (every Windows UA carries "Windows NT") rather than "win",
+// which also matches "Darwin" and would mis-detect macOS as Windows.
+const WINDOWS_UA_RE = /windows/i;
 const RELEASE_NOTES_URL = "https://unsloth.ai/docs/new/changelog";
 const EASE_OUT_QUART: [number, number, number, number] = [0.165, 0.84, 0.44, 1];
 
@@ -38,7 +40,15 @@ export function WebUpdateBanner({
   }
 
   async function handleCopyCommand() {
-    if (!(await copyToClipboard(STUDIO_UPDATE_COPY_CMD))) {
+    // Copy only the command for the user's OS: pasting both (Unix + PowerShell)
+    // into a single terminal runs the wrong one and errors out.
+    const isWindows =
+      typeof navigator !== "undefined" &&
+      WINDOWS_UA_RE.test(navigator.userAgent || "");
+    const command = isWindows
+      ? STUDIO_UPDATE_WINDOWS_CMD
+      : STUDIO_UPDATE_UNIX_CMD;
+    if (!(await copyToClipboard(command))) {
       return;
     }
     setCopiedVersion(status?.latestVersion ?? null);

studio/frontend/src/features/settings/components/update-studio-instructions.tsx

@@ -230,23 +230,6 @@ export function UpdateStudioInstructions({
                   animate={fadeAnimate}
                   exit={fadeExit}
                   transition={fadeTransition}
-                >
-                  <CopyableCommand
-                    command={updateCmd}
-                    copyLabel={t("settings.about.update.localUpdateCommand")}
-                  />
-                </motion.div>
-              </AnimatePresence>
-              <p className="text-xs text-muted-foreground leading-relaxed">
-                {t("settings.about.update.localInstallerFallback")}
-              </p>
-              <AnimatePresence mode="wait" initial={false}>
-                <motion.div
-                  key={`local-fallback-${shell}`}
-                  initial={fadeInitial}
-                  animate={fadeAnimate}
-                  exit={fadeExit}
-                  transition={fadeTransition}
                 >
                   <CopyableCommand
                     command={
@@ -254,7 +237,7 @@ export function UpdateStudioInstructions({
                         ? STUDIO_LOCAL_FALLBACK_WINDOWS_CMD
                         : STUDIO_LOCAL_FALLBACK_UNIX_CMD
                     }
-                    copyLabel={t("settings.about.update.localInstallerCommand")}
+                    copyLabel={t("settings.about.update.localUpdateCommand")}
                   />
                 </motion.div>
               </AnimatePresence>

studio/frontend/src/i18n/locales/en.ts

@@ -307,8 +307,6 @@ export const en = {
           "Pull latest changes from your Unsloth repo checkout, then update Studio locally:",
         gitPullCommand: "git pull command",
         localUpdateCommand: "local update command",
-        localInstallerFallback:
-          "If the Studio update command is unavailable, run the local installer from that checkout:",
         localInstallerCommand: "local installer command",
         sourceInstallDetected:
           "This looks like a source or VCS package install. Reinstall from the original local path or Git URL you used.",

studio/frontend/src/i18n/locales/zh-CN.ts

@@ -288,8 +288,6 @@ export const zhCN = {
           "从你的 Unsloth 仓库 checkout 拉取最新变更，然后本地更新 Studio：",
         gitPullCommand: "git pull 命令",
         localUpdateCommand: "本地更新命令",
-        localInstallerFallback:
-          "如果 Studio 更新命令不可用，请从该 checkout 运行本地安装器：",
         localInstallerCommand: "本地安装器命令",
         sourceInstallDetected:
           "这看起来是源码或 VCS 包安装。请从最初使用的本地路径或 Git URL 重新安装。",