Fix collect endpoint for custom tracker filenames

[benvinegar]

Overview

• derive the collect endpoint as a sibling of the loaded tracker script with the URL API
• support custom tracker filenames while preserving deployment subpaths
• discard script query strings and fragments from the reporting endpoint
• add focused regression coverage for default/custom filenames, subpaths, and query/hash behavior

Closes #243.

Test evidence

• pnpm --filter @counterscale/tracker exec vitest run — 10 files, 135 tests passed
• pnpm --filter @counterscale/tracker typecheck — passed
• pnpm --filter @counterscale/tracker lint — passed with 62 pre-existing warnings and no errors
• pnpm --filter @counterscale/tracker build — passed
• git diff --check — passed

Residual risks

• None identified; endpoint construction relies on the browser-standard URL resolution used by supported runtimes.

This PR description was generated by Pi using OpenAI GPT-5.6 Sol

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.91%. Comparing base (7edfdad) to head (cd7b96b).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #263   +/-   ##
=======================================
  Coverage   83.91%   83.91%           
=======================================
  Files          55       55           
  Lines        1878     1878           
  Branches      517      517           
=======================================
  Hits         1576     1576           
  Misses        266      266           
  Partials       36       36           

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[benvinegar]

Independent browser and network evidence

Verified commit cd7b96b41774062bb7f5934c592dc4bc863966d2 in a real Chromium browser using the tracker bundle built from this PR.

The bundle loaded from nested custom filename:

/deployments/counterscale/assets/custom-analytics-name.js?build=263&channel=review#loader-fragment

It then issued sibling /cache and /collect requests. The script query and fragment did not leak into the reporting endpoint. All 5 custom probe assertions, 135 Vitest tests, and 9 Chromium integration tests passed.

Artifacts:

• HAR
• Playwright trace
• Structured probe report
• Terminal transcript
• Evidence bundle and methodology

Limitation: the independent probe used Chromium on loopback HTTP; WebKit was unavailable.

This comment was generated by Pi using OpenAI GPT-5.6 Sol