Spread AbsolutePathBuf (#17792)

Mechanical change to promote absolute paths through code.

codex-rs/app-server-protocol/schema/json/v2/HookCompletedNotification.json

@@ -1,6 +1,10 @@
 {
   "$schema": "http://json-schema.org/draft-07/schema#",
   "definitions": {
+    "AbsolutePathBuf": {
+      "description": "A path that is guaranteed to be absolute and normalized (though it is not guaranteed to be canonicalized or exist on the filesystem).\n\nIMPORTANT: When deserializing an `AbsolutePathBuf`, a base path must be set using [AbsolutePathBufGuard::new]. If no base path is set, the deserialization will fail unless the path being deserialized is already absolute.",
+      "type": "string"
+    },
     "HookEventName": {
       "enum": [
         "preToolUse",
@@ -103,7 +107,7 @@
           "$ref": "#/definitions/HookScope"
         },
         "sourcePath": {
-          "type": "string"
+          "$ref": "#/definitions/AbsolutePathBuf"
         },
         "startedAt": {
           "format": "int64",