fix: preserve UTM params for backend attribution, only strip ad click IDs

CHANGELOG.md

@@ -16,7 +16,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 - **Marketing parameters no longer fragment your pages.** Pages like `/about?utm_source=google` and `/about?utm_campaign=spring` now correctly show as just `/about` in your Top Pages. UTM tags, Facebook click IDs, Google click IDs, and other tracking parameters are stripped from the page path so all visits to the same page are grouped together.
 - **Trailing slashes no longer split pages.** `/about/` and `/about` now count as the same page instead of appearing as separate entries in your analytics.
 - **Traffic sources are no longer over-counted.** When a visitor arrived from Facebook (or any external source) and browsed multiple pages, every page was credited to Facebook instead of just the first. Now only the landing page shows the referrer, giving you accurate traffic source numbers.
-- **More ad parameters are cleaned from page paths.** Facebook and Meta ad parameters like `ad_id` and `campaign_id` are now stripped, so pages shared across different ad campaigns all show as one entry in your Top Pages.
+- **UTM attribution now works correctly.** Visitors arriving via campaign links (e.g. from Facebook Ads, Google Ads, or email campaigns) now have their traffic source, medium, and campaign properly recorded. Previously, this data was accidentally lost before it reached the server.
+- **More ad tracking clutter removed from page paths.** Facebook ad parameters and click IDs from various platforms are cleaned from your page URLs so your Top Pages stay tidy.
 
 ## [0.15.0-alpha] - 2026-03-13