fix(app-server): fix optional bool annotations (#24099)

`#[serde(default)]` wasn't sufficient for our generated TS types to
reflect that clients didn't have to set them. We also need
`skip_serializing_if = "std::ops::Not::not"`. This is already a rule in
our agents.md file.

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

@@ -2,7 +2,6 @@
   "$schema": "http://json-schema.org/draft-07/schema#",
   "properties": {
     "includeTurns": {
-      "default": false,
       "description": "When true, include turns and their items from rollout history.",
       "type": "boolean"
     },