chore: sync community files

[albert20260301]

Summary

• Add the shared GitHub funding metadata and PR template.
• Refresh CODE_OF_CONDUCT.md and SECURITY.md from the managed workspace templates.

Impact

• Community and policy files only; no runtime Ruby SDK behavior changes.
• Keeps altertable-ruby aligned with the shared SDK community-file baseline.

Verification

• git diff --check
• bundle exec rake could not run because Ruby/Bundler are not installed in this heartbeat environment (ruby, gem, and bundle are unavailable).

[albert20260301]

@leonkenneth could you review this?

I picked you because this is the Ruby SDK and path history for the touched community files only points to prior sync automation. CI is green across lint, semantic title, typing, and the Ruby test matrix. Main review focus is whether these shared community-file updates fit the repo.