feat: replace back button with HomeButton and fix view transition

- Use HomeButton component in HeaderNote for logo, hover, and view-transition-name
- Eagerly import HeaderNote in FluxNote so the logo exists in the DOM when the transition snapshot is taken
- Wait for afterEach + nextTick in the view transition hook to handle lazy-loaded routes
- Add cursor: pointer to font change button

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/router/router.ts

@@ -104,7 +104,12 @@ router.beforeEach(() => {
       }
     ).startViewTransition(async () => {
       resolve()
-      await nextTick()
+      await new Promise<void>((r) => {
+        const unwatch = router.afterEach(() => {
+          unwatch()
+          nextTick().then(r)
+        })
+      })
     })
   })
 })