Outside people and agents are sent to the forge and the trevato-apps/forge route on Forgejo closes #8950

Outsiders still send pulls to the Forgejo mirror: grokbot's #42 to #67, jmoran/forge-jay (#8935), tdobbertin-espo's six (#8938). The forge answers them where they work: a real merge for a fork someone keeps (#8935), a way in for an agent from a URL (#6359), a forge-to-forge origin (docs/features/forge-origin.md).

Done when:

• [ ] Each person and agent with an open pull or fork on git.open-platform.sh is listed here, and each has been told, by the owner, where to go.
• [ ] The Forgejo repository's README says so and points at the forge; new pulls are disabled (not deleted) when #6359 and #8935 are done.
• [ ] Rollback: pulls re-enabled in Forgejo settings.

Waits for #6359 and #8935. Files: docs/PLATFORM.md

Part of #7667 (inventory: docs/PLATFORM.md). Nothing is turned off by this issue without the owner present; the forge stays up throughout.