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/migrations/017_close_reason_column.go

@@ -0,0 +1,31 @@
+package migrations
+
+import (
+	"database/sql"
+	"fmt"
+)
+
+// MigrateCloseReasonColumn adds the close_reason column to the issues table.
+// This column stores the reason provided when closing an issue.
+func MigrateCloseReasonColumn(db *sql.DB) error {
+	var columnExists bool
+	err := db.QueryRow(`
+		SELECT COUNT(*) > 0
+		FROM pragma_table_info('issues')
+		WHERE name = 'close_reason'
+	`).Scan(&columnExists)
+	if err != nil {
+		return fmt.Errorf("failed to check close_reason column: %w", err)
+	}
+
+	if columnExists {
+		return nil
+	}
+
+	_, err = db.Exec(`ALTER TABLE issues ADD COLUMN close_reason TEXT DEFAULT ''`)
+	if err != nil {
+		return fmt.Errorf("failed to add close_reason column: %w", err)
+	}
+
+	return nil
+}