feat: UI polish sprint — 7 items + logs toolbar redesign (#365)

* feat: UI polish sprint — tag filters, toast tokens, logs toolbar, billing portal, editor UX

- Fleet: replace inline tag pills with multi-select combobox dropdown
- Toast: remap all notification colors to oklch design tokens
- Logs: convert floating hover toolbar to permanent pinned toolbar,
  replace all hardcoded colors with design tokens for theme support
- Audit: fix dropdown scroll-lock (modal=false), light theme button contrast
- Resources: remove redundant inner border/bg on tab wrapper
- Editor: add ⌘K/Ctrl+K shortcut hint and handler, standardize button heights
- Billing: signed Lemon Squeezy portal URLs via sencho.io proxy for all tiers
- New MultiSelectCombobox UI component

* feat(editor): replace button row with split-button dropdown

Replace three separate editor buttons (Discard, Save Only, Save & Deploy)
with a compact split-button dropdown. Primary action is "Save & Deploy";
chevron opens dropdown with "Save Only" and "Discard Changes" options.

backend/src/index.ts

@@ -1062,6 +1062,20 @@ app.post('/api/license/validate', async (_req: Request, res: Response): Promise<
   }
 });
 
+app.get('/api/license/billing-portal', async (_req: Request, res: Response): Promise<void> => {
+  try {
+    const url = await LicenseService.getInstance().getBillingPortalUrl();
+    if (!url) {
+      res.status(404).json({ error: 'No billing portal available. Ensure you have an active license.' });
+      return;
+    }
+    res.json({ url });
+  } catch (error) {
+    console.error('[License] Billing portal error:', error);
+    res.status(500).json({ error: 'Failed to retrieve billing portal URL' });
+  }
+});
+
 // --- Self-Update ---
 
 /** Respond 202 and trigger the "last breath" self-update after the response flushes. */