feat: add branch-validate skill

[sunnysingh]

ℹ️ Overview

• adds branch-validate skill: the org branch naming convention plus a validate-branch.sh regex check for an existing or proposed branch name
• symlinked into .agents/skills and .claude/skills, matching how pr-create is wired up
• pr-create now defers to branch-validate instead of restating naming rules
• pr-create diff commands default to origin/main with a note to swap in the repo's actual default branch — they were hardcoded to master

🤖 Coding AI Authorship

• Co-authored: agent wrote meaningful portions, significantly edited by me.

🧪 Test Instructions

Run this skill locally.

For example with Claude Code:

claude /branch-validate

Test Results

📝 Authoring Guidelines

Tip

Read through our full PR Guidelines.

As the author, I verify that I have:

• Followed the test instructions and updated the test results.
• Added/updated unit tests as applicable.
• Added/updated documentation as applicable.

💬 Reviewer Guidelines

Tip

Read through our full PR Guidelines.

Reviewers are responsible for:

• Reading the full PR description.
• Evaluating all code changes, including edge cases and regressions.
• Testing the change (locally or in ephemeral environments, if applicable).
• Leaving thoughtful, actionable feedback.
• Clearly signaling approval or requesting changes.

🚨 Risks

No significant risks — skill docs and a standalone validation script, nothing runs in CI.

[Jarvis-Alloy]

Related Jira Issue: EE-2083 Cursor Cloud Branch/PR Creation Skill.