feat(installer,web): one canonical bundle per target; robust in-place upgrades; update-check feedback (#142)

Co-authored-by: Yaowei Zheng <hiyouga@buaa.edu.cn>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

packages/web/src/lib/strings-en.ts

@@ -67,6 +67,8 @@ export const en: Strings = {
      */
     checkNow: "Check for updates",
     checking: "Checking…",
+    /** Success toast when the manual check finds a newer release; the row below turns into the update entry. */
+    foundNew: (v: string) => `New version v${v} found — use the update entry below to install`,
     upToDate: "You're on the latest version",
     checkFailed: "Update check failed — try again later",
     checkDisabled: "Update checks are disabled (PENGUIN_UPDATE_CHECK=off)",