feat: reinitialize agents when a prebuilt workspace is claimed (#17475)

This pull request allows coder workspace agents to be reinitialized when
a prebuilt workspace is claimed by a user. This facilitates the transfer
of ownership between the anonymous prebuilds system user and the new
owner of the workspace.

Only a single agent per prebuilt workspace is supported for now, but
plumbing has already been done to facilitate the seamless transition to
multi-agent support.

---------

Signed-off-by: Danny Kopping <dannykopping@gmail.com>
Co-authored-by: Danny Kopping <dannykopping@gmail.com>

docs/reference/api/agents.md

@@ -470,6 +470,38 @@ curl -X PATCH http://coder-server:8080/api/v2/workspaceagents/me/logs \
 
 To perform this operation, you must be authenticated. [Learn more](authentication.md).
 
+## Get workspace agent reinitialization
+
+### Code samples
+
+```shell
+# Example request using curl
+curl -X GET http://coder-server:8080/api/v2/workspaceagents/me/reinit \
+  -H 'Accept: application/json' \
+  -H 'Coder-Session-Token: API_KEY'
+```
+
+`GET /workspaceagents/me/reinit`
+
+### Example responses
+
+> 200 Response
+
+```json
+{
+  "reason": "prebuild_claimed",
+  "workspaceID": "string"
+}
+```
+
+### Responses
+
+| Status | Meaning                                                 | Description | Schema                                                                     |
+|--------|---------------------------------------------------------|-------------|----------------------------------------------------------------------------|
+| 200    | [OK](https://tools.ietf.org/html/rfc7231#section-6.3.1) | OK          | [agentsdk.ReinitializationEvent](schemas.md#agentsdkreinitializationevent) |
+
+To perform this operation, you must be authenticated. [Learn more](authentication.md).
+
 ## Get workspace agent by ID
 
 ### Code samples

docs/reference/api/schemas.md

@@ -182,6 +182,36 @@
 | `icon`         | string | false    |              |                                                                                                                                                                                                |
 | `id`           | string | false    |              | ID is a unique identifier for the log source. It is scoped to a workspace agent, and can be statically defined inside code to prevent duplicate sources from being created for the same agent. |
 
+## agentsdk.ReinitializationEvent
+
+```json
+{
+  "reason": "prebuild_claimed",
+  "workspaceID": "string"
+}
+```
+
+### Properties
+
+| Name          | Type                                                               | Required | Restrictions | Description |
+|---------------|--------------------------------------------------------------------|----------|--------------|-------------|
+| `reason`      | [agentsdk.ReinitializationReason](#agentsdkreinitializationreason) | false    |              |             |
+| `workspaceID` | string                                                             | false    |              |             |
+
+## agentsdk.ReinitializationReason
+
+```json
+"prebuild_claimed"
+```
+
+### Properties
+
+#### Enumerated Values
+
+| Value              |
+|--------------------|
+| `prebuild_claimed` |
+
 ## aisdk.Attachment
 
 ```json