docs: clarify /format command is collaborator-only

[Tamcodes4]

Description

Documentation follow-up to #236/#250, updates contributor-facing docs and bot messages to reflect that the /format PR command is now restricted to maintainers/collaborators, not something any contributor can trigger.

Changes Made

• CONTRIBUTING.md: clarifies that external contributors should run Prettier locally; /format is for maintainers/collaborators only.
• contributor-reminder.yml: removed the line inviting contributors to comment /format, since that auto-comment is shown to non-maintainers who can't use it.

Linked Issue

Relates to #236

Type of Change

• Bug fix
• New feature
• UI/Visual update
• Documentation update
• Refactor

Testing

• Tested locally
• Tested on mobile viewport (if applicable)
• No console errors introduced

Validated both files with prettier --check. Confirmed via repo-wide grep that no other docs or workflow messages still reference contributors using /format.

Checklist

• My code follows the project's coding style
• I have formatted my code locally by running npx prettier --write . before submitting
• I am submitting my PR from a dedicated feature/* branch, not the main branch
• I have performed a self-review of my code
• My changes generate no new warnings or errors
• I have updated documentation if required
• I have linked the relevant issue

Screenshots / Screen Recording

N/A, documentation/messaging change only, no UI impact.

[github-actions]

Thank you for submitting a pull request.

Please ensure your changes comply with the project's contribution guidelines and that all workflow checks pass successfully.

Formatting and Branching

• Please confirm you have formatted your code locally using npx prettier --write ., or you can simply comment /format on this PR to have our bot do it for you!
• Ensure this PR is made from a feature/* branch and not main.

Note: This project is currently maintained by a solo maintainer, so reviews and responses may sometimes take a little time. Thanks for your patience.