Add optional argument / environment variable to override PR number

[max-trunk]

In the event that one's CI configuration prevents the environment from setting the PR info needed to detect uploads from PRs, allow users to conditionally set the PR number on PR builds. This will get propagated through the bundle meta's envs and used / preferred when parsing the PR number (and therefore branch class as well) later on in the pipeline

Tested a Bamboo upload where I set TRUNK_PR_NUMBER=1, observed it present in the captured bundle meta env vars:

{"CI": "true", "bamboo_agentId": "3407873", "bamboo_planKey": "TEST-TEST3", "TRUNK_PR_NUMBER": "1", "bamboo_buildKey": "TEST-TEST3-JOB1", "bamboo_planName": "Test - test - new-branch", "bamboo_resultsUrl": "http://172.19.0.3:8085/browse/TEST-TEST3-JOB1-1", "bamboo_buildNumber": "1", "bamboo_shortJobName": "Default Job", "bamboo_shortPlanKey": "TEST3", "bamboo_buildPlanName": "Test - test - new-branch - Default Job", "bamboo_shortPlanName": "test", "bamboo_buildResultKey": "TEST-TEST3-JOB1-1", "bamboo_buildTimeStamp": "2026-02-05T19:07:30.491Z", "bamboo_buildResultsUrl": "http://172.19.0.3:8085/browse/TEST-TEST3-JOB1-1", "bamboo_triggerReason_key": "com.atlassian.bamboo.plugin.system.triggerReason:InitialBuildTriggerReason", "bamboo_shortPlanBranchName": "new-branch", "bamboo_planRepository_branch": "new-branch", "bamboo_planRepository_revision": "a26603e03823c78fa634a811e56c3abbd04922b3", "bamboo_planRepository_username": "max-trunk", "bamboo_planRepository_branchName": "new-branch", "bamboo_planRepository_repositoryUrl": "https://github.com/max-trunk/go-tests.git"}

[trunk-io]

😎 Merged directly without going through the merge queue, as the queue was empty and the PR was up to date with the target branch - details.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 92.30769% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.68%. Comparing base (90c3482) to head (262b7ae).

Files with missing lines	Patch %	Lines
context/src/env/parser.rs	88.23%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1032      +/-   ##
==========================================
+ Coverage   81.40%   81.68%   +0.27%     
==========================================
  Files          69       69              
  Lines       14566    14577      +11     
==========================================
+ Hits        11858    11907      +49     
+ Misses       2708     2670      -38     

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[trunk-staging-io]

     

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[trunk-io]

     

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