ci: enforce PR issue references and branch conventions

Validate BO-<issue>-<slug> branch names and lint PR titles and commit headers in CI and release workflows.

Require GitHub closing-keyword issue references and verify referenced issues exist. Align contributing, release, commit, testing, and policy docs with the enforced behavior and tone.

commitlint.config.cjs

@@ -2,6 +2,8 @@ module.exports = {
   extends: ["@commitlint/config-conventional"],
   rules: {
     "type-enum": [2, "always", ["feat", "fix", "db", "perf", "refactor", "style", "docs", "test", "build", "ci", "chore", "security", "revert"]],
+    "header-max-length": [2, "always", 72],
+    "subject-full-stop": [2, "never", "."],
     "scope-enum": [
       2,
       "always",