chore: use support@wickra.org for contact/author email; drop dead sponsor link (#97)

Now that the wickra.org catch-all mailbox exists, move the project contact +
package-author email off the personal gmail to support@wickra.org across all
surfaces: CODE_OF_CONDUCT, SECURITY, CITATION.cff, Cargo.toml, the npm + PyPI
author fields, the release.yml npm author, and repo-metadata.toml. (The
package-author changes take effect on the next published release.)

repo-metadata.toml's [audit].forbidden still pins kingchencp@gmail.com (the
private commit email) as a banned substring — unchanged.

Also remove the FUNDING.yml custom "https://wickra.org/sponsor" entry: that
page 404s, so the Sponsor button linked to a dead URL. The GitHub Sponsors
entry (github: [kingchenc]) stays.

CODE_OF_CONDUCT.md

@@ -33,7 +33,7 @@ project in public spaces.
 ## Enforcement
 
 Instances of unacceptable behaviour may be reported to the project maintainer
-at **wickra.lib@gmail.com**. All reports will be reviewed and investigated
+at **support@wickra.org**. All reports will be reviewed and investigated
 promptly and fairly, and the maintainer will respect the privacy and security
 of the reporter.