fix(site): exclude workspace schedule settings for prebuilt workspaces (#18826)

## Description

This PR updates the UI to avoid rendering workspace schedule settings
(autostop, autostart, etc.) for prebuilt workspaces. Instead, it
displays an informational message with a link to the relevant
documentation.

## Changes

* Introduce `IsPrebuild` parameter to `convertWorkspace` to indicate
whether the workspace is a prebuild.
* Prevent the Workspace Schedule settings form from rendering in the UI
for prebuilt workspaces.
* Display an info alert with a link to documentation when viewing a
prebuilt workspace.

<img width="2980" height="864" alt="Screenshot 2025-07-10 at 13 16 13"
src="https://github.com/user-attachments/assets/5f831c21-50bb-4e05-beea-dbeb930ddff8"
/>


Relates with: https://github.com/coder/coder/pull/18762

---------

Co-authored-by: BrunoQuaresma <bruno_nonato_quaresma@hotmail.com>

coderd/apidoc/docs.go

@@ -17653,6 +17653,10 @@ const docTemplate = `{
                     "type": "string",
                     "format": "uuid"
                 },
+                "is_prebuild": {
+                    "description": "IsPrebuild indicates whether the workspace is a prebuilt workspace.\nPrebuilt workspaces are owned by the prebuilds system user and have specific behavior,\nsuch as being managed differently from regular workspaces.\nOnce a prebuilt workspace is claimed by a user, it transitions to a regular workspace,\nand IsPrebuild returns false.",
+                    "type": "boolean"
+                },
                 "last_used_at": {
                     "type": "string",
                     "format": "date-time"

coderd/apidoc/swagger.json

@@ -16116,6 +16116,10 @@
 					"type": "string",
 					"format": "uuid"
 				},
+				"is_prebuild": {
+					"description": "IsPrebuild indicates whether the workspace is a prebuilt workspace.\nPrebuilt workspaces are owned by the prebuilds system user and have specific behavior,\nsuch as being managed differently from regular workspaces.\nOnce a prebuilt workspace is claimed by a user, it transitions to a regular workspace,\nand IsPrebuild returns false.",
+					"type": "boolean"
+				},
 				"last_used_at": {
 					"type": "string",
 					"format": "date-time"

coderd/workspaces.go

@@ -2231,6 +2231,7 @@ func convertWorkspace(
 	if latestAppStatus.ID == uuid.Nil {
 		appStatus = nil
 	}
+
 	return codersdk.Workspace{
 		ID:                                   workspace.ID,
 		CreatedAt:                            workspace.CreatedAt,
@@ -2265,6 +2266,7 @@ func convertWorkspace(
 		AllowRenames:     allowRenames,
 		Favorite:         requesterFavorite,
 		NextStartAt:      nextStartAt,
+		IsPrebuild:       workspace.IsPrebuild(),
 	}, nil
 }