Relates to CODAGT-713
Depends on #27515
This adds `--agents-allowed` to `coder templates create` and `coder templates edit`. Template creation defaults the option to true, matching the per-template API and database default, while template editing only changes the value when the flag is explicitly supplied so unrelated edits preserve the existing setting.
The generated CLI help and reference documentation include the new option. #27518 updates the Coder Agents platform controls documentation to describe the completed per-template model.
Ethan