Read writeOnly so required write-only fields don't break response schemas #63

Forge doesn't read writeOnly, so a required write-only field stays required in response schemas. The API never returns these fields, so every real response fails.

Example: hyperdrive-database-full requires password, which is writeOnly ("The API never returns this write-only value"). Every Hyperdrive config response schema then requires origin.password.

12 schemas in the spec have a required writeOnly field.

Fix: add Field::is_write_only, like is_read_only, so generators can drop these fields from responses.

Found by the response checks in cloudflare/mcp#301.