Add local system usernames to PII/safe-list guidance in issue-create

[LeanAndMean]

Summary

The commands/issue-create.md PII guardrails (added in PR #133) do not explicitly address local system usernames (e.g., jsmith in /home/jsmith/repos/project). File paths are on the safe-list and "internal hostnames/IPs" is on the sensitive list, but embedded local usernames occupy a gray area between these two categories.

Current Behavior

Local system usernames appearing in file paths are implicitly covered by the "file paths" safe-list entry, but the relationship is not explicitly stated. Issue #84's acceptance criteria mention "local usernames" as a category to review for.

Proposed Behavior

Add explicit guidance for local system usernames -- most likely a parenthetical on the safe-list entry: "file paths (including embedded local usernames)" since they typically only appear as path components and are not independently sensitive in a developer-tool context.

Acceptance Criteria

• Local system usernames are explicitly addressed in either the PII-sensitive list or the safe-list in commands/issue-create.md
• The chosen placement is justified relative to the file-path safe-list entry

Context

• Identified during PR Add content-quality guardrails to issue-create command #133 review (finding S4)
• Related to issue Add guardrails to issue-create for PII, premature solutions, and acceptance criteria #84 acceptance criteria item 1