feat(fleet): tidy the Overview toolbar and shorten tab labels (#1361)

- Move the Add node button into the Overview toolbar beside the
  Grid/Topology toggle so it sits with the view it acts on instead of
  showing on every Fleet tab. It stays admin-only.
- Collapse the node search to an icon button that expands to the full
  input on click and collapses again on blur once the query is empty,
  reclaiming toolbar width. An active query keeps it open.
- Match the sort-direction toggle and the sort dropdown to the outlined
  dark fill of the Filters button for a consistent toolbar row.
- Swap the Check Updates icon to the refresh-with-dot glyph.
- Rename two tabs: Fleet Actions to Actions, Dependencies to Map
  (display labels only; internal keys unchanged).

Update the feature docs to the new tab labels.

docs/features/stack-labels.mdx

@@ -85,7 +85,7 @@ A stack can carry multiple labels and will then appear under each label's group
   The Fleet Actions cards run admin-only on every tier. Operator and viewer roles see the cards but cannot apply them.
 </Note>
 
-Two cards in the **Fleet · Fleet Actions** tab use labels to drive cross-node operations. See [Fleet Actions](/features/fleet-actions) for the full reference.
+Two cards in the **Fleet · Actions** tab use labels to drive cross-node operations. See [Fleet Actions](/features/fleet-actions) for the full reference.
 
 <Frame>
   <img src="/images/stack-labels/fleet-actions.png" alt="Fleet Actions tab with two cards side by side. Left card 'Stop fleet by label' (rose accent rail) has a Label name combobox containing 'Media' and a Stop matching stacks button beneath. Right card 'Bulk label assign' (purple accent rail) has a node selector reading Local (local), a stacks checklist showing plex and radarr ticked, a Labels row with a highlighted Media pill plus inactive Network and Utilities, and an Apply to 3 stacks button." />