feat(ui): enhance workspace status and diff styling

This commit updates several UI components to improve visual consistency and readability across various themes. It adds necessary class names to the Git branch display component and significantly refines the CSS for diff markers and general workspace status elements. These changes ensure that semantic colors are maintained on hover states and that key indicators remain highly visible in light mode.

- Updated styling for diff marker focus/hover states
- Improved visual feedback for line patch buttons (stage, unstage, discard)
- Added specific light theme styles for branch indicator and status counters

src/App.svelte

@@ -4103,7 +4103,7 @@
       {/if}
       <span class="workspace-status-spacer"></span>
       {#if workspaceActive}
-        <span><GitBranch size={12} aria-hidden="true" />{status?.current_branch ?? "No branch"}</span>
+        <span class="workspace-branch"><GitBranch size={12} aria-hidden="true" />{status?.current_branch ?? "No branch"}</span>
         <span class="ahead">↑ {status?.ahead ?? 0}</span>
         <span class="behind">↓ {status?.behind ?? 0}</span>
         <span class:active={autoRefreshEnabled} class="workspace-auto">Auto <i aria-hidden="true"></i></span>