feat: add today's run count and avg floor stat queries

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

store/stats.go

@@ -0,0 +1,48 @@
+package store
+
+import (
+	"encoding/json"
+	"time"
+
+	bolt "go.etcd.io/bbolt"
+)
+
+// GetTodayRunCount returns the number of daily challenge runs for today.
+func (d *DB) GetTodayRunCount() (int, error) {
+	today := time.Now().Format("2006-01-02")
+	count := 0
+	err := d.db.View(func(tx *bolt.Tx) error {
+		b := tx.Bucket(bucketDailyRuns)
+		c := b.Cursor()
+		prefix := []byte(today + ":")
+		for k, _ := c.Seek(prefix); k != nil && len(k) >= len(prefix) && string(k[:len(prefix)]) == string(prefix); k, _ = c.Next() {
+			count++
+		}
+		return nil
+	})
+	return count, err
+}
+
+// GetTodayAvgFloor returns the average floor reached in today's daily runs.
+func (d *DB) GetTodayAvgFloor() (float64, error) {
+	today := time.Now().Format("2006-01-02")
+	total := 0
+	count := 0
+	err := d.db.View(func(tx *bolt.Tx) error {
+		b := tx.Bucket(bucketDailyRuns)
+		c := b.Cursor()
+		prefix := []byte(today + ":")
+		for k, v := c.Seek(prefix); k != nil && len(k) >= len(prefix) && string(k[:len(prefix)]) == string(prefix); k, v = c.Next() {
+			var r DailyRecord
+			if json.Unmarshal(v, &r) == nil {
+				total += r.FloorReached
+				count++
+			}
+		}
+		return nil
+	})
+	if count == 0 {
+		return 0, err
+	}
+	return float64(total) / float64(count), err
+}