Add codex_hook_run analytics event (#17996)

# Why
Add product analytics for hook handler executions so we can understand
which hooks are running, where they came from, and whether they
completed, failed, stopped, or blocked work.

# What
- add the new `codex_hook_run` analytics event and payload plumbing in
`codex-rs/analytics`
- emit hook-run analytics from the shared hook completion path in
`codex-rs/core`
- classify hook source from the loaded hook path as `system`, `user`,
`project`, or `unknown`

```
{
  "event_type": "codex_hook_run",
  "event_params": {
    "thread_id": "string",
    "turn_id": "string",
    "model_slug": "string",
    "hook_name": "string, // any HookEventName
    "hook_source": "system | user | project | unknown",
    "status": "completed | failed | stopped | blocked"
  }
}
```

---------

Co-authored-by: Codex <noreply@openai.com>

codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.schemas.json

@@ -8597,6 +8597,14 @@
           "scope": {
             "$ref": "#/definitions/v2/HookScope"
           },
+          "source": {
+            "allOf": [
+              {
+                "$ref": "#/definitions/v2/HookSource"
+              }
+            ],
+            "default": "unknown"
+          },
           "sourcePath": {
             "$ref": "#/definitions/v2/AbsolutePathBuf"
           },
@@ -8635,6 +8643,19 @@
         ],
         "type": "string"
       },
+      "HookSource": {
+        "enum": [
+          "system",
+          "user",
+          "project",
+          "mdm",
+          "sessionFlags",
+          "legacyManagedConfigFile",
+          "legacyManagedConfigMdm",
+          "unknown"
+        ],
+        "type": "string"
+      },
       "HookStartedNotification": {
         "$schema": "http://json-schema.org/draft-07/schema#",
         "properties": {