feat(stats): switch to aggregate component for O(log n) counts

- Add @convex-dev/aggregate package for efficient aggregation
- Update convex.config.ts with pageViewsByPath, totalPageViews, uniqueVisitors aggregates
- Update recordPageView to insert into aggregate components
- Update getStats to use aggregate counts instead of O(n) table scans
- Add backfillAggregates internal mutation for existing data
- Update prds/howstatsworks.md with old vs new comparison
- Update changelog.md with v1.11.0 entry
- Update files.md with aggregate component info

package.json

@@ -17,6 +17,7 @@
     "deploy:prod": "npx convex deploy && npm run sync:prod"
   },
   "dependencies": {
+    "@convex-dev/aggregate": "^0.2.0",
     "@mendable/firecrawl-js": "^1.21.1",
     "@phosphor-icons/react": "^2.1.10",
     "@radix-ui/react-icons": "^1.3.2",