* feat: add conventional-branch skill
Add a new agent skill for creating Git branches following the
Conventional Branch specification. The skill covers branch naming
rules, valid/invalid examples, type prefixes (feature/, bugfix/,
hotfix/, release/, chore/), trunk branch detection, and a
step-by-step workflow for branch creation.
The skill complements the existing conventional-commit skill and
references the specification at https://conventional-branch.github.io.
* fix: use explicit numbered workflow steps in conventional-branch skill
Replace markdown heading-based workflow steps (### 1., ### 2.)
with explicit 'Step N — Title' format for better agent
comprehension.
Xianpeng Shen