fix: evaluate shortcodes in field default value

[faisalahammad]

Description

When a field has Allow Shortcodes enabled and a shortcode is set in its Default Value, the shortcode stayed literal in the form until the item was first saved. The per-type {type}_allow_shortcode flag was only read in each field's display() method, not in the central PodsForm::default_value() resolver that runs at form render time.

Fix: evaluate the shortcode in PodsForm::default_value() when the field type opts in, nested inside the existing default_evaluate_tags block so only the configured default is processed, never request-supplied values.

Single-point fix in the central resolver covers every caller: the frontend form (classes/PodsForm.php:258), the three PodsAPI::save_post sites (classes/PodsAPI.php:5078, 5105, 5191), and PodsField::build_dfv_field_data() (classes/PodsField.php:475).

Backward compatibility:

• do_shortcode() is idempotent. Unregistered shortcodes return unchanged.
• pods_form_field_default_value filter preserved at same priority.
• Smart Tags {@...} still resolved first.
• Field types without {type}_allow_shortcode (e.g. pick, file, number) untouched.
• Request-supplied defaults via default_value_parameter stay literal (security).

Related GitHub issue(s)

Fixes #7021

Testing instructions

1. In WP admin, create a Pod named "Plants" with a Plain Text field.
2. Edit the Plain Text field options. Enable Allow Shortcodes.
3. Set Default Value to Today is [current_year] (or any shortcode registered on the site).
4. Save the Pod.
5. Create a new Plants item.
6. The form field should render as Today is 2026, not the literal [current_year].
7. Save the item. Frontend display still shows the year.
8. Repeat with Allow Shortcodes off. Form shows the literal [current_year] (pre-fix behavior).
9. Repeat with a pick field whose default is [anything]. Literal text preserved (no pick_allow_shortcode option).

PHP tests (run via SLIC):

slic run wpunit --ext DotReporter

JS tests:

npm run jest

Screenshots / screencast

Not applicable (no UI change visible to end users; the fix only changes what text is rendered in the form input on new item creation).

Changelog text for these changes

Bug: Shortcodes in Pods field Default Value are now evaluated in the form when Allow Shortcodes is enabled. #7021

PR checklist

• I have tested my own code to confirm it works as I intended.
• My code follows the WordPress Coding Standards.
• My code follows the WordPress Inline Documentation Standards.
• My code includes automated tests for PHP and/or JS (if applicable).

[faisalahammad]

AI disclosure: this PR was written with Claude Opus 5 assistance, reviewed and tested by me.