Add comprehensive validation system with runtime configuration

Implements a flexible validation framework for student rankings, team assignments, and team composition with administrator-configurable rules and thresholds.

Validation System:
- Reflection-based rule discovery eliminates manual registration
- Base classes (RequiredEventTypeRuleBase, EventCountThresholdRuleBase) reduce code duplication by ~250 lines
- 12 validation rules covering event requirements, counts, and team constraints
- Configurable severity levels (Warning/Error) per rule type
- ValidationService with caching for optimal performance
- Rules apply contextually (StudentRanking, StudentAssignment, TeamComposition)

Configuration & Admin UI:
- ValidationSettings admin page for editing thresholds and severity levels
- ChapterSettings admin page for editing chapter information
- Settings stored in Data/appsettings.json for runtime configuration
- JSON config works in both development and production environments
- Auto-creates Data directory and config template on first run

User Experience:
- ValidationWarnings component displays inline warnings/errors
- Integrated in Event Ranking, Registration, and Team Assignment pages
- Color-coded severity indicators (warning yellow, error red)
- Includes "Too Many Regional Events" rule (max 3 recommended)

Technical Improvements:
- Template Method pattern for rule base classes
- Singleton rule instances with lazy initialization
- Configuration loaded via IConfiguration with fallback to defaults
- Safe JSON updates preserve other appsettings sections

WebApp/Components/Pages/Home.razor

@@ -26,6 +26,9 @@
     </div>
 </MudPaper>
 
+<MudPaper Elevation="0" Class="mb-6">
+<MudText Typo="Typo.h4" Class="mb-2">Data</MudText>
+</MudPaper>
 <MudGrid>
     <!-- Events Card -->
     <DashboardCard Icon="@AppIcons.Events"
@@ -60,13 +63,19 @@
                    Subtitle="Total Teams"
                    Caption="@($"{_groupTeamsCount} Team | {_individualTeamsCount} Individual")"
                    NavigateUrl="/teams" />
-
-    <!-- Meeting Schedule Card -->
-    <DashboardCard Icon="@AppIcons.Scheduler"
-                   Title="Schedule"
-                   Caption="Optimize meeting times"
-                   NavigateUrl="/meeting-schedule" />
 </MudGrid>
+<MudPaper Elevation="0" Class="my-6">
+    <MudText Typo="Typo.h4">Tools</MudText>
+</MudPaper>
+
+    <MudGrid>
+
+        <!-- Meeting Schedule Card -->
+        <DashboardCard Icon="@AppIcons.Scheduler"
+                       Title="Schedule"
+                       Caption="Optimize meeting times"
+                       NavigateUrl="/meeting-schedule"/>
+    </MudGrid>
 
 @code {
     private int _eventCount;