Improve UI design system and fix notification positioning

- Overhaul CSS with comprehensive design tokens (shadows, transitions, radii)
- Add hover effects and smooth transitions to cards, buttons, tables
- Improve typography hierarchy and color consistency
- Remove inline styles from 10 template files for better maintainability
- Add global notification container to ensure toasts appear above modals
- Update showNotification/showAlert functions to use centralized container
- Add accessibility improvements (focus states, reduced motion support)
- Improve responsive design and mobile styling
- Add print styles

app/web/templates/alerts.html

@@ -5,7 +5,7 @@
 {% block content %}
 <div class="row mt-4">
     <div class="col-12 d-flex justify-content-between align-items-center mb-4">
-        <h1 style="color: #60a5fa;">Alert History</h1>
+        <h1>Alert History</h1>
         <a href="{{ url_for('main.alert_rules') }}" class="btn btn-primary">
             <i class="bi bi-gear"></i> Manage Alert Rules
         </a>
@@ -18,7 +18,7 @@
         <div class="card">
             <div class="card-body">
                 <h6 class="text-muted mb-2">Total Alerts</h6>
-                <h3 class="mb-0" style="color: #60a5fa;">{{ pagination.total }}</h3>
+                <h3 class="mb-0">{{ pagination.total }}</h3>
             </div>
         </div>
     </div>
@@ -46,7 +46,7 @@
         <div class="card">
             <div class="card-body">
                 <h6 class="text-muted mb-2">Unacknowledged</h6>
-                <h3 class="mb-0" style="color: #f97316;">
+                <h3 class="mb-0 text-warning">
                     {{ alerts | rejectattr('acknowledged') | list | length }}
                 </h3>
             </div>
@@ -104,7 +104,7 @@
     <div class="col-12">
         <div class="card">
             <div class="card-header">
-                <h5 class="mb-0" style="color: #60a5fa;">Alerts</h5>
+                <h5 class="mb-0">Alerts</h5>
             </div>
             <div class="card-body">
                 {% if alerts %}