## Why
The schema exporter sits on application builds' critical path, but compiling it as a test harness also compiles and registers unit tests that schema generation does not need.
## What changed
Build the exporter with `--cfg=test` to retain test-only schema derives without the test harness, and disable its debug metadata. Run schema generation directly on a thread with an 8 MiB stack.
Share the environment-driven schema writer with the existing ignored test, allow a configurable crate root in `schema_sources`, and switch the public schema bundle to the dedicated generator.
GitOrigin-RevId: 317e24f77e153b9ba0c5c583837eed3bcd3774fd
## 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
jif