feat: add filter support for DOK awards

The DOK award type (used for DLD award) now supports filtering by band,
mode, and other QSO fields. This allows creating award variants like:
- DLD on specific bands (80m, 40m, etc.)
- DLD on specific modes (CW, SSB, etc.)
- DLD with combined filters (e.g., 80m + CW)

Changes:
- Modified calculateDOKAwardProgress() to apply filters before processing
- Added example awards: dld-80m, dld-40m, dld-cw, dld-80m-cw
- Filter system uses existing applyFilters() function

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

award-definitions/dld-80m-cw.json

@@ -0,0 +1,20 @@
+{
+  "id": "dld-80m-cw",
+  "name": "DLD 80m CW",
+  "description": "Confirm 100 unique DOKs on 80m using CW",
+  "caption": "Contact and confirm stations with 100 unique DOKs (DARC Ortsverband Kennung) on the 80m band using CW mode. Only DCL-confirmed QSOs with valid DOK information on 80m CW count toward this award.",
+  "category": "darc",
+  "rules": {
+    "type": "dok",
+    "target": 100,
+    "confirmationType": "dcl",
+    "displayField": "darcDok",
+    "filters": {
+      "operator": "AND",
+      "filters": [
+        { "field": "band", "operator": "eq", "value": "80m" },
+        { "field": "mode", "operator": "eq", "value": "CW" }
+      ]
+    }
+  }
+}