fix(library): address review findings in AGENTS.md and errata.md

Update AGENTS.md file tree to include repair workflow steps and other
missing files. Add context note to errata Step 7 explaining why library
job setup is part of the repair workflow.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: ncrmro

src/deepwork/standard_jobs/deepwork_jobs/steps/errata.md

@@ -178,6 +178,8 @@ Check for and remove other obsolete files:
 
 ### Step 7: Library Job Access via Nix Dev Shell
 
+Library jobs replace some patterns previously handled by copied job files. This step ensures users are aware of the recommended setup path.
+
 Check whether the project uses a Nix flake devshell and whether shared library jobs are configured.
 
 **Detection logic:**