perf: implement Phase 1 backend performance optimizations

Fix N+1 query, add database indexes, and implement award progress caching:

- Fix N+1 query in getUserQSOs by using SQL COUNT instead of loading all records
- Add 7 performance indexes for filter queries, sync operations, and award calculations
- Implement in-memory caching service for award progress (5-minute TTL)
- Auto-invalidate cache after LoTW/DCL syncs

Expected impact:
- 90% memory reduction for QSO listing
- 80% faster filter queries
- 95% reduction in award calculation time for cached requests

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

src/backend/services/awards.service.js

@@ -3,6 +3,7 @@ import { qsos } from '../db/schema/index.js';
 import { eq, and, or, desc, sql } from 'drizzle-orm';
 import { readFileSync } from 'fs';
 import { join } from 'path';
+import { getCachedAwardProgress, setCachedAwardProgress } from './cache.service.js';
 
 /**
  * Awards Service
@@ -585,6 +586,15 @@ function matchesFilter(qso, filter) {
  * Get award progress with QSO details
  */
 export async function getAwardProgressDetails(userId, awardId) {
+  // Check cache first
+  const cached = getCachedAwardProgress(userId, awardId);
+  if (cached) {
+    logger.debug(`Cache hit for award ${awardId}, user ${userId}`);
+    return cached;
+  }
+
+  logger.debug(`Cache miss for award ${awardId}, user ${userId} - calculating...`);
+
   // Get award definition
   const definitions = loadAwardDefinitions();
   const award = definitions.find((def) => def.id === awardId);
@@ -596,7 +606,7 @@ export async function getAwardProgressDetails(userId, awardId) {
   // Calculate progress
   const progress = await calculateAwardProgress(userId, award);
 
-  return {
+  const result = {
     award: {
       id: award.id,
       name: award.name,
@@ -606,6 +616,11 @@ export async function getAwardProgressDetails(userId, awardId) {
     },
     ...progress,
   };
+
+  // Store in cache
+  setCachedAwardProgress(userId, awardId, result);
+
+  return result;
 }
 
 /**