[build-tools] Add eas/posthog_upload_sourcemaps workflow function

[gwdp]

Why

Upload your app's source maps to PostHog from a workflow, so error-tracking stack traces are readable instead of minified. For EAS Update and custom builds, where the automatic build-time upload doesn't run.

How

Adds eas/posthog_upload_sourcemaps. Runs @posthog/cli hermes upload against a directory (default dist) with the connect step's POSTHOG_CLI_* creds. Chunk IDs are injected at bundle time by PostHog's Expo metro config (getPostHogExpoConfig), so this step just ships what's already in the export.

ignore_error (default false) fails the step on an upload error; set it true to warn and continue.
(This is the outlier of the posthog functions, but felt the right call, defaults to fail; Lmk if different thoughts)

Test Plan

CI passes. Ran it live against coin-flip with the metro config in place: expo export --source-maps then this step uploaded the Hermes map to PostHog (Found 1 maps to upload, 1 upload keys). Test workflow below covers the happy path plus a forced failure and an ignored one.

Test workflow

name: PostHog source map upload test

jobs:
  upload_sourcemaps:
    environment: production
    steps:
      - uses: eas/checkout
      - run: npm ci
      - run: npx expo export --source-maps --platform ios
      - uses: eas/posthog_upload_sourcemaps
        with:
          directory: dist

  upload_failure:
    environment: production
    steps:
      - uses: eas/posthog_upload_sourcemaps
        with:
          directory: does-not-exist

  ignored_failure:
    environment: production
    steps:
      - uses: eas/posthog_upload_sourcemaps
        with:
          directory: does-not-exist
          ignore_error: true

[linear-code]

ENG-21551

[gwdp]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• [build-tools] Add eas/posthog_wait_for_query workflow function #3949
• [build-tools] Add eas/posthog_annotation workflow function #3948
• [build-tools] Add eas/posthog_upload_sourcemaps workflow function #3947 👈 (View in Graphite)
• [build-tools] Add eas/posthog_wait_for_metric workflow function #3945
• [build-tools] Add eas/posthog_flag_rollout workflow function #3944
• [build-tools] Add eas/posthog_capture_event workflow function #3934
• main

This stack of pull requests is managed by Graphite. Learn more about stacking.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 59.71%. Comparing base (bc4056b) to head (d089cc8).

Additional details and impacted files

@@                            Coverage Diff                             @@
##           gwdp/eng-21551-posthog-wait-for-metric    #3947      +/-   ##
==========================================================================
+ Coverage                                   59.69%   59.71%   +0.03%     
==========================================================================
  Files                                         942      943       +1     
  Lines                                       41555    41579      +24     
  Branches                                     8757     8758       +1     
==========================================================================
+ Hits                                        24802    24826      +24     
  Misses                                      16659    16659              
  Partials                                       94       94              

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[github-actions]

Subscribed to pull request

File Patterns	Mentions
**/*	@douglowder

Generated by CodeMention

Warning: The preamble and epilogue options in commentConfiguration are deprecated. Use template instead.

[sjchmiela]

i think we might need -y?

[github-actions]

✅ Thank you for adding the changelog entry!