Feature/glassmorphism unified UI (#507)

* feat(frontend): unified glassmorphism UI rework with bug fixes

- Create _glass-system.scss unified design system (~450 lines)
  - CSS custom properties for glass tokens (bg, blur, shadow, border)
  - Theme-aware variables (dark/light) eliminating manual overrides
  - Glass surface mixins (subtle/medium/strong variants)
  - Component classes, button system, form elements, utilities

- Fix notification bell click-outside bug
  - Replace broken querySelector with Vue template refs
  - Add @click.stop modifier and onUnmounted cleanup
  - Make bell visible on all screen sizes (was hidden on mobile)

- Fix login state refresh bug
  - LoginView now uses useAuth().login() composable
  - Replace window.location.href with router.push('/')
  - Auth state updates reactively via module-level singleton refs

- Remove duplicate hamburger menu navigation
  - Delete mobile menu overlay, hamburger button, related functions
  - SidebarNav for desktop, BottomNav for mobile (clean separation)

- Migrate 13 components to glass system variables
  - Replace hardcoded rgba/blur/shadow with glass tokens
  - Remove [data-theme] overrides (glass vars are theme-aware)
  - Add @supports fallbacks for backdrop-filter

- Remove old _glass.scss import from main.scss (dead code)

* feat: add .gitignore to exclude cache and project.local.yml

* feat: update .gitignore to include .pytest_cache and .serena

Author: Serph91P

.gitignore

@@ -109,4 +109,6 @@ recordings/
 temp_logs
 logs_local
 data_local
-.pytest_cache
+.pytest_cache
+
+.serena

.serena/.gitignore

@@ -0,0 +1,2 @@
+/cache
+/project.local.yml