fix: sync ID counters after import to prevent collisions

When importing issues with explicit high IDs (e.g., bd-100), the
issue_counters table wasn't being updated. This caused the next
auto-generated issue to collide with existing IDs (bd-4 instead of bd-101).

Changes:
- Add SyncAllCounters() to scan all issues and update counters atomically
- Add SyncCounterForPrefix() for granular counter synchronization
- Call SyncAllCounters() in import command after creating issues
- Add comprehensive tests for counter sync functionality
- Update TestImportCounterSyncAfterHighID to verify fix

The fix uses a single efficient SQL query to prevent ID collisions
with subsequently auto-generated issues.

internal/storage/sqlite/sqlite.go

@@ -107,6 +107,22 @@ func (s *SQLiteStorage) getNextIDForPrefix(ctx context.Context, prefix string) (
 	return nextID, nil
 }
 
+// SyncCounterForPrefix synchronizes the counter to be at least the given value
+// This is used after importing issues with explicit IDs to prevent ID collisions
+// with subsequently auto-generated IDs
+func (s *SQLiteStorage) SyncCounterForPrefix(ctx context.Context, prefix string, minValue int) error {
+	_, err := s.db.ExecContext(ctx, `
+		INSERT INTO issue_counters (prefix, last_id)
+		VALUES (?, ?)
+		ON CONFLICT(prefix) DO UPDATE SET
+			last_id = MAX(last_id, ?)
+	`, prefix, minValue, minValue)
+	if err != nil {
+		return fmt.Errorf("failed to sync counter for prefix %s: %w", prefix, err)
+	}
+	return nil
+}
+
 // SyncAllCounters synchronizes all ID counters based on existing issues in the database
 // This scans all issues and updates counters to prevent ID collisions with auto-generated IDs
 func (s *SQLiteStorage) SyncAllCounters(ctx context.Context) error {