Bugfix: Network pane stuck on old host after mount success

- `NetworkMountView.handleShareSelect` cleared its local `currentNetworkHost`
  after a successful mount but didn't propagate the null via
  `onNetworkHostChange`. The parent `FilePane` kept the stale host in its
  own `$state`, so the next time the user switched back to Network (for
  example, in a subsequent test), `NetworkMountView` was re-mounted with
  `initialNetworkHost = <old host>` and rendered `ShareBrowser` for the old
  host instead of the host list. In E2E, `move_cursor("SMB Test (Unicode)")`
  then had no effect (ShareBrowser has no such share) and
  `open_under_cursor` opened the wrong entry. Add `onNetworkHostChange(null)`
  so the parent stays in sync.
- `ShareBrowser.loadShares` also now retries for cached non-auth errors
  (`host_unreachable`, `timeout`, ...) instead of rendering the cached
  error directly. User-initiated host open is an implicit "try again" —
  the initial background prefetch may have run before the host was ready.
- Fixes `smb.spec.ts:436` "unicode shares render correctly" when run in
  the full suite.

Author: vdavid

apps/desktop/src/lib/file-explorer/network/ShareBrowser.svelte

@@ -170,11 +170,13 @@
                 }
                 // No stored credentials, show login form
                 showLoginForm = true
+                error = cachedState.error
+                loading = false
+                return
             }
-            // No stored credentials or they didn't work
-            error = cachedState.error
-            loading = false
-            return
+            // Non-auth error (host_unreachable, timeout, etc.): the user is
+            // explicitly opening the host, so retry. The initial background
+            // prefetch may have run before the host was ready.
         }
 
         // Fetch shares

apps/desktop/src/lib/file-explorer/pane/NetworkMountView.svelte

@@ -121,9 +121,13 @@
             )
 
             // Navigate to the mounted share
-            // Clear current network host first
+            // Clear current network host first (also propagate up so the parent
+            // pane's state doesn't hold onto a stale host; otherwise the next
+            // time the user switches back to Network, ShareBrowser for the old
+            // host would render instead of the NetworkBrowser list).
             currentNetworkHost = null
             lastMountAttempt = null
+            onNetworkHostChange?.(null)
 
             // The mount path is typically /Volumes/<ShareName>
             const mountPath = result.mountPath