feat(cli): add --no-wait flag to coder create (#22867)

Adds a `--no-wait` flag (CODER_CREATE_NO_WAIT) to the create command,
matching the existing pattern in `coder start`. When set, the `coder
create` command returns immediately after the workspace creation API
call succeeds instead of streaming build logs until completion.

This enables fire-and-forget workspace creation in CI/automation
contexts (e.g., GitHub Actions), where waiting for the build to finish
is unnecessary. Combined with other existing flags, users can create a
workspace with no interactivity, assuming the user is already
authenticated.

docs/reference/cli/external-workspaces_create.md

@@ -92,6 +92,15 @@ Specify the source workspace name to copy parameters from.
 
 Automatically accept parameter defaults when no value is provided.
 
+### --no-wait
+
+|             |                                    |
+|-------------|------------------------------------|
+| Type        | <code>bool</code>                  |
+| Environment | <code>$CODER_CREATE_NO_WAIT</code> |
+
+Return immediately after creating the workspace. The build will run in the background.
+
 ### -y, --yes
 
 |      |                   |