Enhance UI: favicon, AgentDetail overhaul, PageTabBar, and config form

Add favicon and web manifest branding assets. Major AgentDetail page
rework with tabbed sections, run history, and live status. Add
PageTabBar component for consistent page-level tabs. Expand
AgentConfigForm with more adapter fields. Improve NewAgentDialog,
OnboardingWizard, and Issues page layouts.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

ui/public/site.webmanifest

@@ -0,0 +1,19 @@
+{
+  "name": "Paperclip",
+  "short_name": "Paperclip",
+  "icons": [
+    {
+      "src": "/android-chrome-192x192.png",
+      "sizes": "192x192",
+      "type": "image/png"
+    },
+    {
+      "src": "/android-chrome-512x512.png",
+      "sizes": "512x512",
+      "type": "image/png"
+    }
+  ],
+  "theme_color": "#18181b",
+  "background_color": "#18181b",
+  "display": "standalone"
+}