fix(cli): allow site admins to use coder create --org for any organization (#21528)

## Problem

Site-wide admins (e.g., Owners) could not use `coder create --org <org>`
to create workspaces in organizations they are not members of. The error
was:

```
$ coder create my-workspace -t docker --org data-science
error: organization "data-science" not found, are you sure you are a member of this organization?
```

This was inconsistent with the web UI, where Owners can create
workspaces in any organization.

## Root Cause

The CLI's `OrganizationContext.Selected()` function only checked the
user's membership list, ignoring site-wide RBAC permissions that grant
Owners access to all organizations.

## Solution

Added a fallback in `OrganizationContext.Selected()` that fetches the
org directly via the API when not found in the membership list. This
works because the API endpoint applies RBAC filtering, allowing Owners
to read any org.

## Impact

This fixes `coder create --org` and all other CLI commands that use
`OrganizationContext.Selected()` (29+ commands), including:
- `coder templates push --org <any-org>`
- `coder organizations members add --org <any-org>`
- `coder provisioner list --org <any-org>`

## Testing

Added `TestEnterpriseCreate/OwnerCanCreateInNonMemberOrg` which:
- Creates an Owner user who is NOT a member of a second org
- Verifies they can create a workspace there using `--org`
- Properly fails without the code fix, passes with it

---

*This PR was generated by [mux](https://mux.coder.com) but reviewed by a
human.*

cli/root.go

@@ -884,16 +884,27 @@ func (o *OrganizationContext) Selected(inv *serpent.Invocation, client *codersdk
 		index := slices.IndexFunc(orgs, func(org codersdk.Organization) bool {
 			return org.Name == o.FlagSelect || org.ID.String() == o.FlagSelect
 		})
+		if index >= 0 {
+			return orgs[index], nil
+		}
 
-		if index < 0 {
+		// Not in membership list - try direct fetch.
+		// This allows site-wide admins (e.g., Owners) to use orgs they aren't
+		// members of.
+		org, err := client.OrganizationByName(inv.Context(), o.FlagSelect)
+		if err != nil {
 			var names []string
 			for _, org := range orgs {
 				names = append(names, org.Name)
 			}
-			return codersdk.Organization{}, xerrors.Errorf("organization %q not found, are you sure you are a member of this organization? "+
-				"Valid options for '--org=' are [%s].", o.FlagSelect, strings.Join(names, ", "))
+			var sdkErr *codersdk.Error
+			if errors.As(err, &sdkErr) && sdkErr.StatusCode() == http.StatusNotFound {
+				return codersdk.Organization{}, xerrors.Errorf("organization %q not found, are you sure you are a member of this organization? "+
+					"Valid options for '--org=' are [%s].", o.FlagSelect, strings.Join(names, ", "))
+			}
+			return codersdk.Organization{}, xerrors.Errorf("get organization %q: %w", o.FlagSelect, err)
 		}
-		return orgs[index], nil
+		return org, nil
 	}
 
 	if len(orgs) == 1 {