Create community health files for arch3.js

## Description

Create [community health files](https://docs.github.com/en/communities/setting-up-your-project-for-healthy-contributions/creating-a-default-community-health-file).

**Files:**

- CODE_OF_CONDUCT.md
- CONTRIBUTING.md
- SECURITY.md
- SUPPORT.md
- [Issue and pull request templates](https://docs.github.com/en/communities/using-templates-to-encourage-useful-issues-and-pull-requests/about-issue-and-pull-request-templates)

### Issues templates

- Bug Report
- Feature Request

### Pull Requests template

Use [Cosmos SDK files](https://github.com/cosmos/cosmos-sdk/tree/main/.github) as examples.

Review the linked Cosmos SDK .github files first to compare the community health files and template structure. Create CODE_OF_CONDUCT.md, CONTRIBUTING.md, SECURITY.md, SUPPORT.md, bug and feature issue templates, and a pull request template; done means every listed file is present and reflects the project’s contribution guidance.

Written by the indexing model from the issue text.