feat: Enhance Marketplace and Skill Management UI with improved error handling and user feedback

- Updated MarketplaceDrawer to include security notes and manual installation hints.
- Refactored SkillDetailDrawer to display default icons for skills.
- Simplified SkillListItem to use default icons for better readability.
- Integrated gateway status checks and warnings in SkillsPage for improved user awareness.
- Enhanced error handling for skill installation and fetching, providing clearer feedback to users.
- Added new translations for error messages and gateway warnings to improve localization support.

resources/skills/preinstalled-manifest.json

@@ -0,0 +1,68 @@
+{
+  "skills": [
+    {
+      "slug": "pdf",
+      "repo": "anthropics/skills",
+      "repoPath": "skills/pdf",
+      "ref": "main",
+      "version": "main",
+      "autoEnable": true
+    },
+    {
+      "slug": "xlsx",
+      "repo": "anthropics/skills",
+      "repoPath": "skills/xlsx",
+      "ref": "main",
+      "version": "main",
+      "autoEnable": true
+    },
+    {
+      "slug": "docx",
+      "repo": "anthropics/skills",
+      "repoPath": "skills/docx",
+      "ref": "main",
+      "version": "main",
+      "autoEnable": true
+    },
+    {
+      "slug": "pptx",
+      "repo": "anthropics/skills",
+      "repoPath": "skills/pptx",
+      "ref": "main",
+      "version": "main",
+      "autoEnable": true
+    },
+    {
+      "slug": "find-skills",
+      "repo": "vercel-labs/skills",
+      "repoPath": "skills/find-skills",
+      "ref": "main",
+      "version": "main",
+      "autoEnable": true
+    },
+    {
+      "slug": "self-improving-agent",
+      "repo": "peterskoett/self-improving-agent",
+      "repoPath": ".",
+      "ref": "master",
+      "version": "main",
+      "autoEnable": true
+    },
+    {
+      "slug": "tavily-search",
+      "repo": "tavily-ai/skills",
+      "repoPath": "skills/tavily-search",
+      "ref": "main",
+      "version": "main",
+      "autoEnable": true
+    },
+    {
+      "slug": "brave-web-search",
+      "repo": "brave/brave-search-skills",
+      "repoPath": "skills/web-search",
+      "ref": "main",
+      "version": "main",
+      "autoEnable": true
+    }
+  ]
+}