Bump releaseo to v0.0.3 and preserve original release actor through workflow chain

[danbarr]

Summary

Adds workflow steps to preserve the GitHub actor who triggered the release workflow, passing it through to downstream workflows like docs-website updates.

Bumps releaseo action to v0.0.3 which introduced this capability.

Problem

When using the new release workflow:

1. User triggers create-release-pr.yml via workflow_dispatch → github.actor is the user
2. Release PR is merged, triggering create-release-tag.yml which creates the release using RELEASE_TOKEN
3. releaser.yml is triggered by the release event → github.actor is now stacklokbot (the PAT owner)

This breaks PR assignment in the docs-website repo, which receives stacklokbot instead of the original triggering user.

Solution

1. releaseo adds a Release-Triggered-By: username git trailer to commits
2. create-release-tag.yml extracts the trailer and embeds it in the release body as an HTML comment
3. releaser.yml parses the release body and passes the original actor to downstream workflows

Changes

• create-release-tag.yml: Extract Release-Triggered-By trailer, embed in release body
• releaser.yml: Add extract-release-actor job, use extracted actor for docs update and Slack notifications

Dependencies

Important

This PR is blocked on:

• Add git trailer to preserve workflow triggering actor releaseo#21 - Add Release-Triggered-By git trailer
• Bump stacklok/releaseo action version in create-release-pr.yml after release

Test Plan

• Verify releaseo adds the trailer to commits
• Verify create-release-tag.yml extracts trailer and includes in release body
• Verify releaser.yml extracts actor from release body
• Verify docs-website PR is assigned to correct user

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 65.55%. Comparing base (a73bf3d) to head (84237dd).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3560      +/-   ##
==========================================
+ Coverage   65.47%   65.55%   +0.08%     
==========================================
  Files         404      404              
  Lines       39781    39781              
==========================================
+ Hits        26047    26079      +32     
+ Misses      11720    11689      -31     
+ Partials     2014     2013       -1     

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