feat(integration): add Pinterest _epik click ID capture

[jciafardone]

Add Pinterest _epik parameter mapping to integrationMappingExternal.

• Added _epik parameter mapping to capture Pinterest click IDs
• Maps to Pinterest.click_id in custom flags
• Supports capture from query parameters, cookies, and localStorage

Reference: https://help.pinterest.com/en/business/article/add-event-codes

Testing:

• Added comprehensive tests covering all three capture sources
• Tests verify proper mapping to custom flags
• All existing tests continue to pass

Background

• Pinterest requires the _epik parameter to be captured and sent as Pinterest.click_id custom flag for Pinterest Conversions API (CAPI) integration
• Currently, the SDK captures click IDs for Facebook, Google, TikTok, and Snapchat, but not Pinterest
• This change adds Pinterest to the list of supported integration-specific identifier captures
• Reference: https://help.pinterest.com/en/business/article/add-event-codes

What Has Changed

• Added _epik parameter mapping to integrationMappingExternal in integrationCapture.ts
• Maps _epik to Pinterest.click_id custom flag
• Supports capture from URL query parameters, cookies, and localStorage
• Follows standard priority resolution: query params > localStorage > cookies
• Outputs to CUSTOM_FLAGS (consistent with other click ID integrations like gclid, fbclid, ttclid)
• No processor function needed (unlike Facebook's fbclid which requires formatting)

Screenshots/Video

• N/A (backend integration change)

Checklist

• I have performed a self-review of my own code.
• I have made corresponding changes to the documentation.
• I have added tests that prove my fix is effective or that my feature works.
• I have tested this locally.

Additional Notes

• Tested extraction logic locally using standalone browser test file
• Verified capture from URL query params, cookies, and localStorage
• Confirmed priority resolution works correctly (query > localStorage > cookie)
• Validated custom flag mapping to Pinterest.click_id
• This change is additive and does not affect existing integrations
• No breaking changes introduced

Reference Issue (For employees only. Ignore if you are an outside contributor)

• Closes https://go/j/[ticket-number]

[sonarqubecloud]

Quality Gate passed

Issues
8 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud