Align repository GitHub policy with Base

[codeforester]

Align base-bash-libs with the current Base repository GitHub workflow and default-branch policy.

Scope:

• match the Base issue-first, category-label, Project-status, PR-body, and cleanup guidance where applicable;
• make the manifest-driven PR sections consistent with Base while preserving library-specific API/release concerns;
• document the modest default-branch baseline: pull requests and issue-branch policy are enforced, while Tests/Quality remain release evidence;
• update the live classic branch-protection settings to match Base (zero required approvals, no required CI contexts, administrators enforced, strict status configuration retained);
• preserve the branch naming ruleset and the single-file-library/release/security policies unique to base-bash-libs.

This is a policy-alignment change, not a reduction in release validation. The full test and quality workflows continue to run and remain release gates.