fix: add SQLite database recovery and WAL mode for corruption resilience

- Add scripts/db-recovery.sh for database integrity check and recovery
- Enable WAL mode verification with logging on startup
- Add structured error logging to uptime handlers with monitor context
- Add comprehensive database maintenance documentation

Fixes heartbeat history showing "No History Available" due to database
corruption affecting 6 out of 14 monitors.

backend/internal/database/database.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"strings"
 
+	"github.com/Wikid82/charon/backend/internal/logger"
 	"gorm.io/driver/sqlite"
 	"gorm.io/gorm"
 )
@@ -43,6 +44,14 @@ func Connect(dbPath string) (*gorm.DB, error) {
 	}
 	configurePool(sqlDB)
 
+	// Verify WAL mode is enabled and log confirmation
+	var journalMode string
+	if err := db.Raw("PRAGMA journal_mode").Scan(&journalMode).Error; err != nil {
+		logger.Log().WithError(err).Warn("Failed to verify SQLite journal mode")
+	} else {
+		logger.Log().WithField("journal_mode", journalMode).Info("SQLite database connected with WAL mode enabled")
+	}
+
 	return db, nil
 }