fix(deps): exclude relates-to from cycle detection (fixes #661)

relates-to dependencies are intentionally bidirectional ("see also" links)
and should not be reported as cycles by bd dep cycles. This matches the
existing behavior in AddDependency which already skips cycle prevention
for relates-to.

Changes:
- Filter relates-to edges in DetectCycles SQL query
- Add tests for relates-to exclusion from cycle detection
- Update existing test to reflect correct behavior

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

internal/storage/sqlite/dependencies.go

@@ -613,9 +613,12 @@ func (s *SQLiteStorage) GetDependencyTree(ctx context.Context, issueID string, m
 }
 
 // DetectCycles finds circular dependencies and returns the actual cycle paths
+// Note: relates-to dependencies are excluded because they are intentionally bidirectional
+// ("see also" relationships) and do not represent problematic cycles.
 func (s *SQLiteStorage) DetectCycles(ctx context.Context) ([][]*types.Issue, error) {
 	// Use recursive CTE to find cycles with full paths
 	// We track the path as a string to work around SQLite's lack of arrays
+	// Exclude relates-to dependencies since they are inherently bidirectional
 	rows, err := s.db.QueryContext(ctx, `
 		WITH RECURSIVE paths AS (
 			SELECT
@@ -625,6 +628,7 @@ func (s *SQLiteStorage) DetectCycles(ctx context.Context) ([][]*types.Issue, err
 				issue_id || '→' || depends_on_id as path,
 				0 as depth
 			FROM dependencies
+			WHERE type != 'relates-to'
 
 			UNION ALL
 
@@ -636,7 +640,8 @@ func (s *SQLiteStorage) DetectCycles(ctx context.Context) ([][]*types.Issue, err
 			p.depth + 1
 			FROM dependencies d
 			JOIN paths p ON d.issue_id = p.depends_on_id
-			WHERE p.depth < ?
+			WHERE d.type != 'relates-to'
+			AND p.depth < ?
 			AND (d.depends_on_id = p.start_id OR p.path NOT LIKE '%' || d.depends_on_id || '→%')
 		)
 		SELECT DISTINCT path as cycle_path