Consolidate tabs, Quick Access links, mini player nav, link descriptions

- Merge Scripts/Callbacks/Links tabs into single Settings tab with collapsible sections
- Rename Actions tab to Quick Access showing both scripts and configured links
- Add prev/next buttons to mini (secondary) player
- Add optional description field to links (backend + frontend)
- Add CSS chevron indicators on collapsible settings sections
- Persist section collapse/expand state in localStorage
- Fix race condition in Quick Access rendering with generation counter
- Order settings sections: Scripts, Links, Callbacks

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

media_server/static/locales/en.json

@@ -116,11 +116,13 @@
   "callbacks.confirm.unsaved": "You have unsaved changes. Are you sure you want to discard them?",
   "tab.player": "Player",
   "tab.browser": "Browser",
-  "tab.quick_actions": "Actions",
-  "tab.scripts": "Scripts",
-  "tab.callbacks": "Callbacks",
-  "tab.links": "Links",
+  "tab.quick_access": "Quick Access",
+  "tab.settings": "Settings",
   "tab.display": "Display",
+  "settings.section.scripts": "Scripts",
+  "settings.section.callbacks": "Callbacks",
+  "settings.section.links": "Links",
+  "quick_access.no_items": "No quick actions or links configured",
   "display.loading": "Loading monitors...",
   "display.error": "Failed to load monitors",
   "display.no_monitors": "No monitors detected",
@@ -179,10 +181,12 @@
   "links.field.url": "URL *",
   "links.field.icon": "Icon (MDI)",
   "links.field.label": "Label",
+  "links.field.description": "Description",
   "links.placeholder.name": "Only letters, numbers, and underscores allowed",
   "links.placeholder.url": "https://example.com",
   "links.placeholder.icon": "mdi:link",
   "links.placeholder.label": "Tooltip text",
+  "links.placeholder.description": "What does this link point to?",
   "links.button.cancel": "Cancel",
   "links.button.save": "Save",
   "links.button.edit": "Edit",