fix: update sliding sync known issues link to #39 (#519)

<!-- Please read
https://github.com/SableClient/Sable/blob/dev/CONTRIBUTING.md before
submitting your pull request -->

### Description

The "Known issues" link in the Experimental Settings page for Sliding
Sync pointed to the old repository (`7w1/sable#146`). This updates it to
the correct issue in the current repository.

#### Type of change

- [x] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to not work as expected)
- [ ] This change requires a documentation update

### Checklist:

- [x] My code follows the style guidelines of this project
- [x] I have performed a self-review of my own code
- [ ] I have commented my code, particularly in hard-to-understand areas
- [ ] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings

### AI disclosure:

- [x] Partially AI assisted (clarify which code was AI assisted and
briefly explain what it does).
- [ ] Fully AI generated (explain what all the generated code does in
moderate detail).

<!-- Write any explanation required here, but do not generate the
explanation using AI!! You must prove you understand what the code in
this PR does. -->

AI was used to locate the old link in the codebase. The change itself is
a one-line URL update in `General.tsx` — no logic is involved.

Author: 7w1

.changeset/fix-sliding-sync-known-issues-link.md

@@ -0,0 +1,5 @@
+---
+default: patch
+---
+
+Fix broken link to Sliding Sync known issues — now points to SableClient/Sable#39 instead of the old repository.

src/app/features/settings/general/General.tsx

@@ -1119,7 +1119,11 @@ export function Sync() {
                   More info/Documentation
                 </a>
                 .{' '}
-                <a href="https://github.com/7w1/sable/issues/146" target="_blank" rel="noreferrer">
+                <a
+                  href="https://github.com/SableClient/Sable/issues/39"
+                  target="_blank"
+                  rel="noreferrer"
+                >
                   Known issues (Sable GitHub)
                 </a>
                 .