PM-35200 - Create contributing guide for Claude tooling

[theMickster]

🎟️ Tracking

PM-35200

📔 Objective

Craft guidance for engineers to understand contributing to Claude tooling.
Adding it to the template so that all future repos have the guidance.
The guidance in the other-side-of-the-coin for ai-plugins/pull/88.
The guidance is a generic application of the work done for the server repo in server/pull/7508.

[github-actions]

🤖 Bitwarden Claude Code Review

Overall Assessment: APPROVE

This PR adds .claude/CONTRIBUTING.md, a 101-line documentation-only guide explaining how engineers should contribute Claude tooling to this repo. The guide covers when to contribute here vs. bitwarden/ai-plugins, how to choose scope and shape (CLAUDE.md, rules, skills, agents, commands, hooks), security conventions for vault/auth/crypto-touching skills, and an iterative build workflow. The content is grounded, follows the active-voice style it advocates, and links to canonical Anthropic and Bitwarden references.

Code Review Details

No findings. The change is documentation-only with no code, dependency, or security surface. Title and description (with Jira tracking and cross-repo context) are adequate; no test plan is needed for a docs-only change.

[github-actions]

Checkmarx One – Scan Summary & Details – 478f9a83-38d2-4069-b8f4-a345f0db5d5b

Great job! No new security vulnerabilities introduced in this pull request

[SaintPatrck]

❓ Why is this +101 but bitwarden/sdk-internal#1008 is +130? Do those larger PR's need to have prettier run on them, or does this repo have different prettier rules?

[theMickster]

I ran prettier on all of those repos's PRs and this one. I also saw similar minor differences.
I didn't dig too deep, but I think the answer to your second question is Yes.