fix(db): add close_reason column to issues table (bd-uyu)

- Add migration 017_close_reason_column.go to create the column
- Update all INSERT statements to include close_reason
- Update all SELECT statements to include close_reason
- Update doctor.go to check for close_reason in schema validation
- Remove workaround code that batch-loaded close reasons from events table
- Fix migrations_test.go to include close_reason in test table schema

This fixes sync loops where close_reason values were silently dropped
because the DB lacked the column despite the struct having the field.

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

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

internal/storage/sqlite/multirepo.go

@@ -241,14 +241,14 @@ func (s *SQLiteStorage) upsertIssueInTx(ctx context.Context, tx *sql.Tx, issue *
 			INSERT INTO issues (
 				id, content_hash, title, description, design, acceptance_criteria, notes,
 				status, priority, issue_type, assignee, estimated_minutes,
-				created_at, updated_at, closed_at, external_ref, source_repo
-			) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
+				created_at, updated_at, closed_at, external_ref, source_repo, close_reason
+			) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
 		`,
 			issue.ID, issue.ContentHash, issue.Title, issue.Description, issue.Design,
 			issue.AcceptanceCriteria, issue.Notes, issue.Status,
 			issue.Priority, issue.IssueType, issue.Assignee,
 			issue.EstimatedMinutes, issue.CreatedAt, issue.UpdatedAt,
-			issue.ClosedAt, issue.ExternalRef, issue.SourceRepo,
+			issue.ClosedAt, issue.ExternalRef, issue.SourceRepo, issue.CloseReason,
 		)
 		if err != nil {
 			return fmt.Errorf("failed to insert issue: %w", err)