Precompute app-server protocol exports (#36212)

## Why

Normal app-server protocol builds do not need the `ts-rs` and `schemars`
implementations used to generate schema exports.

## What changed

- Embed compressed stable and experimental TypeScript and JSON schema exports,
  and serve the existing export APIs from those artifacts.
- Use no-op schema derives in non-test builds while keeping the real generators
  available for fixture regeneration and tests.
- Move schema fixture regeneration behind a Python helper and update
  `just write-app-server-schema --experimental` to refresh the experimental
  embedded exports.

## Testing

- Verify embedded exports match freshly generated stable and experimental
  schemas.
- Verify export options and on-disk output remain compatible.

GitOrigin-RevId: e8536338b457e6eec34bdf29ec0684144bd13734

codex-rs/app-server-protocol/src/protocol/v2/apps.rs

@@ -1,9 +1,9 @@
 use super::shared::default_enabled;
-use schemars::JsonSchema;
+use crate::JsonSchema;
+use crate::TS;
 use serde::Deserialize;
 use serde::Serialize;
 use std::collections::HashMap;
-use ts_rs::TS;
 
 #[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Default, JsonSchema, TS)]
 #[serde(rename_all = "camelCase")]