Fix default values not rendering in backfill options form

[Copilot]

Backfill attributes with default values (e.g., attribute :dry_run, :boolean, default: true) were not displaying their defaults in the UI form.

Root Cause

The backfill_option_inputs helper accessed backfill_run.options[name] directly, returning nil for empty options hashes instead of the attribute's default value.

Changes

• Helper: Instantiate backfill_options_class to leverage ActiveModel::Attributes default value handling

  # Before: raw hash access ignores defaults
  backfill_run.options[name]  # => nil
  
  # After: instance method respects defaults
  options_instance = backfill_run.backfill_class.backfill_options_class.new(backfill_run.options || {})
  options_instance.public_send(name)  # => true (for default: true)

• Tests: Added coverage for boolean, string, and other attribute types with defaults

Affects all attribute types with defaults (boolean, string, integer, etc.), not just booleans.

Preview

Before	After

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