fix(snippetz): escape quotes and backslashes in php/curl request bodies - #10495

Problem

The PHP cURL code example puts request bodies inside a single quoted PHP string without escaping them. If a plain text body, an octet-stream body, or a JSON body that can't be parsed contains an apostrophe or a backslash, the generated code is not valid PHP. For example, the text it's fine becomes 'it's fine', which is a syntax error when a user copies it.

Other PHP targets (guzzle, laravel) already escape these values.

Solution

Use the existing objectToString helper from libs/php for these three body paths. It escapes backslashes and single quotes, the same way the guzzle and laravel examples do. Output for normal bodies does not change.

I added tests for a plain text body, an unparsable JSON body and an octet-stream body. All three fail without the fix.

Checklist

• I explained why the change is needed.
• I added a changeset.
• I added tests.
• I updated the documentation. (not needed, no docs describe this)