fix: disable boot reconciler, fix onboarding loop, UI polish

Critical flow fixes:
- Disable boot reconciliation that auto-created ALL containers on
  unbundled installs (only FileBrowser should exist on first boot)
- Fix onboarding loop: RootRedirect no longer clears the
  neode_onboarding_complete flag on boot screen completion
- Seed phrase persists when navigating back (no regeneration)

UI fixes:
- Boot screen: removed github and save icons from animation loop
- Seed screens: viewport height scaling with 100dvh
- Seed restore: removed outer card container from word input grid
- Seed screens use distinct background (bg-intro-1.jpg)
- Install progress simplified to "Installing" button style
- Uninstall state moved to global store (persists across navigation)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

neode-ui/src/components/BootScreen.vue

@@ -79,8 +79,6 @@ const glitching = ref(false)
 const iconSources = [
   '/assets/icon/bitcoin.svg',
   '/assets/icon/cloud-done.svg',
-  '/assets/icon/github.svg',
-  '/assets/icon/save.svg',
 ]
 
 interface LogLine { prefix: string; text: string; type: string }