fix(core): fixed keyboard shortcut help for Windows and Linux (#14088)

This PR is related to issue
https://github.com/toeverything/AFFiNE/issues/13290

Keyboard shortcut for copying a private link works as expected, but the
overview of shortcuts shows the Mac shortcut for Windows, web and Linux
users. This fix shows the correct (Ctrl+Shift+C) shortcut to the
aforementioned users.

I have not tested this on a Mac (neither in browser nor in the app), but
ideally this should not have an impact for Mac users as the logic for
showing the correct shortcut is already implemented.

Affected files: 
- packages/frontend/core/src/components/hooks/affine/use-shortcuts.ts


Old: 
<img width="1402" height="946" alt="old_shortcut"
src="https://github.com/user-attachments/assets/5c8f2133-2b4d-49c7-8054-851c7de8f3cd"
/>

New:
<img width="650" height="379" alt="Keyboard shortcut fix"
src="https://github.com/user-attachments/assets/a29e2f7a-53d7-4743-a9b1-aa30e7622dd1"
/>


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **Bug Fixes**
* Corrected the keyboard shortcut for copying private links on Windows
from Command+Shift+C to Ctrl+Shift+C.

<sub>✏️ Tip: You can customize this high-level summary in your review
settings.</sub>

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/frontend/core/src/components/hooks/affine/use-shortcuts.ts

@@ -86,7 +86,7 @@ export const useWinGeneralKeyboardShortcuts = (): ShortcutMap => {
       [t('expandOrCollapseSidebar')]: ['Ctrl', '/'],
       [t('goBack')]: ['Ctrl', '['],
       [t('goForward')]: ['Ctrl', ']'],
-      [t('copy-private-link')]: ['⌘', '⇧', 'C'],
+      [t('copy-private-link')]: ['Ctrl', '⇧', 'C'],
     }),
     [t]
   );