fix: use smart default for displayField based on entityType

When displayField is omitted in award definitions, the backend now
selects the appropriate default field based on the entityType:
- dxcc → entity (country name)
- state → state
- grid → grid (4-character)
- callsign → callsign

Previously, it used a fixed fallback order that prioritized entity
over other fields, causing grid-based awards to show DXCC names.

Co-Authored-By: Claude <noreply@anthropic.com>

src/backend/services/awards.service.js

@@ -896,7 +896,19 @@ export async function getAwardEntityBreakdown(userId, awardId) {
       }
       displayName = String(rawValue || entity);
     } else {
-      displayName = qso.entity || qso.state || qso.grid || qso.callsign || String(entity);
+      // Smart default based on entityType when displayField is not specified
+      const defaultDisplayField = {
+        'dxcc': 'entity',
+        'state': 'state',
+        'grid': 'grid',
+        'callsign': 'callsign'
+      }[rules.entityType] || 'entity';
+
+      let rawValue = qso[defaultDisplayField];
+      if (defaultDisplayField === 'grid' && rawValue && rawValue.length > 4) {
+        rawValue = rawValue.substring(0, 4);
+      }
+      displayName = String(rawValue || entity);
     }
 
     if (!slotMap.has(slotKey)) {

src/frontend/src/routes/admin/awards/[id]/+page.svelte

@@ -804,7 +804,7 @@
                   bind:value={formData.rules.displayField}
                   placeholder="e.g., entity, state, grid"
                 />
-                <small>Field to display as entity name (defaults to entity value)</small>
+                <small>Field to display as entity name (defaults based on entityType)</small>
               </div>
 
               <div class="form-group">

src/frontend/src/routes/admin/awards/components/TestAwardModal.svelte

@@ -197,16 +197,22 @@
     }
 
     // Check if displayField matches the default for the entity type
-    if (rules.entityType && rules.displayField) {
+    if (rules.entityType) {
       const defaults = {
         'dxcc': 'entity',
         'state': 'state',
         'grid': 'grid',
         'callsign': 'callsign'
       };
-      if (defaults[rules.entityType] === rules.displayField) {
+      const defaultField = defaults[rules.entityType];
+
+      if (rules.displayField) {
+        if (defaultField === rules.displayField) {
           info.push(`displayField="${rules.displayField}" is the default for entityType="${rules.entityType}". It can be omitted.`);
         }
+      } else if (defaultField) {
+        info.push(`displayField will default to "${defaultField}" for entityType="${rules.entityType}".`);
+      }
     }
 
     return { warnings, info };

src/frontend/src/routes/admin/awards/create/+page.svelte

@@ -829,7 +829,7 @@
                   bind:value={formData.rules.displayField}
                   placeholder="e.g., entity, state, grid"
                 />
-                <small>Field to display as entity name (defaults to entity value)</small>
+                <small>Field to display as entity name (defaults based on entityType)</small>
               </div>
 
               <div class="form-group">