A scoped label like area:permissions was substituted into the branch
name verbatim, producing a ":" that validateBranchName rejects. Because
the branch setup block catches that error and calls process.exit(1), the
whole run died. {{description}} was already sanitized via extractDescription;
{{label}} was the only free-text variable that skipped it.
Add a sanitizeLabel helper (replaces invalid-char runs with a hyphen so
scoped labels stay readable) and apply it before substitution, falling back
to entityType when a label sanitizes to empty. Adds regression tests that
also assert the result passes validateBranchName.
* Add branch-name-template config option
* Logging
* Use branch name template
* Add label to template variables
* Add description template variable
* More concise description for branch_name_template
* Remove more granular time template variables
* Only fetch first label
* Add check for empty template-generated name
* Clean up comments, docstrings
* Merge createBranchTemplateVariables into generateBranchName
* Still replace undefined values
* Fall back to default on duplicate branch
* Parameterize description wordcount
* Remove some over-explanatory comments
* NUM_DESCRIPTION_WORDS: 3 -> 5
