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/Models/AppIcons.cs

@@ -17,9 +17,9 @@ namespace WebApp.Models
             
             return loe switch
             {
-                1 => "‧",
-                2 => "⁚",
-                3 => "⁝",
+                1 => "1",
+                2 => "2",
+                3 => "3",
                 _ => Icons.Material.Filled.QuestionMark
             };
         }

WebApp/Models/ChapterSettings.cs

@@ -0,0 +1,37 @@
+namespace WebApp.Models;
+
+/// <summary>
+/// Configuration for chapter-specific information
+/// </summary>
+public class ChapterSettings
+{
+    /// <summary>
+    /// Full chapter name (e.g., "Your Chapter Name")
+    /// </summary>
+    public string Name { get; set; } = "Your Chapter Name";
+
+    /// <summary>
+    /// Short chapter name abbreviation (e.g., "YCN")
+    /// </summary>
+    public string ShortName { get; set; } = "YCN";
+
+    /// <summary>
+    /// National chapter ID (4 digits, e.g., "0000")
+    /// </summary>
+    public string NationalId { get; set; } = "0000";
+
+    /// <summary>
+    /// State chapter ID (5 digits, e.g., "00000")
+    /// </summary>
+    public string StateId { get; set; } = "00000";
+
+    /// <summary>
+    /// Regional chapter ID (5 digits, e.g., "00000")
+    /// </summary>
+    public string RegionalId { get; set; } = "00000";
+
+    /// <summary>
+    /// Competition year (e.g., "2026")
+    /// </summary>
+    public string CompetitionYear { get; set; } = "2026";
+}