fix: improve Instance settings section spacing and save UX

- Section headings: text-lg with descriptions, dividers spaced my-10
- GeneralPanel: convert to auto-save (toggles save immediately,
  text fields save on blur) — no more hidden save bar
- StreamingPanel: restore sticky save bar (complex multi-field form
  needs explicit save, and it's the only sticky bar now)

packages/web/src/components/modals/instanceSettingsPanels/StreamingPanel.tsx

@@ -489,21 +489,23 @@ export function StreamingPanel() {
         <div className="p-2 bg-status-online/10 border border-status-online/30 rounded text-status-online text-sm">Settings saved</div>
       )}
       {hasChanges && (
-        <div className="flex justify-center pt-3 pb-1">
-          <div className="glass-bubble rounded-full px-4 py-2 flex items-center gap-2 animate-slide-up">
-            <button
-              onClick={handleReset}
-              className="px-3 py-1 text-sm text-txt-tertiary hover:text-txt-secondary transition-colors"
-            >
-              Reset
-            </button>
-            <button
-              onClick={handleSave}
-              disabled={saving}
-              className="px-3 py-1.5 bg-accent-primary hover:bg-accent-primary/80 text-white text-sm font-medium rounded-full transition-colors disabled:opacity-50"
-            >
-              {saving ? 'Saving...' : 'Save'}
-            </button>
+        <div className="sticky bottom-0 z-10 pointer-events-none">
+          <div className="flex justify-center pt-3 pb-1">
+            <div className="glass-bubble rounded-full px-4 py-2 flex items-center gap-2 animate-slide-up pointer-events-auto">
+              <button
+                onClick={handleReset}
+                className="px-3 py-1 text-sm text-txt-tertiary hover:text-txt-secondary transition-colors"
+              >
+                Reset
+              </button>
+              <button
+                onClick={handleSave}
+                disabled={saving}
+                className="px-3 py-1.5 bg-accent-primary hover:bg-accent-primary/80 text-white text-sm font-medium rounded-full transition-colors disabled:opacity-50"
+              >
+                {saving ? 'Saving...' : 'Save'}
+              </button>
+            </div>
           </div>
         </div>
       )}