[codex] Add chart output expression dialog support

[mbakgun]

Summary

• Add chartOutput to the properties panel expression-dialog open/navigation flow.
• Convert chart output text/path/field/unit/title inputs to ExpressionInput so double-click opens the evaluate dialog.
• Build the visible field list dynamically from chart type so dialog prev/next follows the currently rendered fields.

Why

Chart output widget nodes had plain inputs, so double-click did not open the expression dialog like other canvas nodes.

Validation

• SECRET_KEY=test-secret-key-for-tests-only-32-bytes ./check.sh