Adds three community health files flagged by the GitHub repo scan:
- CODE_OF_CONDUCT.md: Contributor Covenant v2.1 verbatim, with the
enforcement contact set to conduct@getpad.dev (matches the domain
used for security@getpad.dev in SECURITY.md).
- .github/CODEOWNERS: default catch-all routing review requests to
@xarmian so PRs auto-request the maintainer.
- .github/FUNDING.yml: enables the Sponsor button on the repo via
github: xarmian; other platforms left commented for future.
Parent: PLAN-644.
xarmian