chore: release v0.12.0

[acp-release-bot]

🤖 New release

• agent-client-protocol-schema: 0.11.7 -> 0.12.0 (⚠ API breaking changes)

⚠ agent-client-protocol-schema breaking changes

--- failure enum_missing: pub enum removed or renamed ---

Description:
A publicly-visible enum cannot be imported by its prior path. A `pub use` may have been removed, or the enum itself may have been renamed or removed entirely.
        ref: https://doc.rust-lang.org/cargo/reference/semver.html#item-remove
       impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.46.0/src/lints/enum_missing.ron

Failed in:
  enum agent_client_protocol_schema::OutgoingMessage, previously in file /tmp/.tmpUxFicl/agent-client-protocol-schema/src/rpc.rs:109

--- failure struct_missing: pub struct removed or renamed ---

Description:
A publicly-visible struct cannot be imported by its prior path. A `pub use` may have been removed, or the struct itself may have been renamed or removed entirely.
        ref: https://doc.rust-lang.org/cargo/reference/semver.html#item-remove
       impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.46.0/src/lints/struct_missing.ron

Failed in:
  struct agent_client_protocol_schema::AgentSide, previously in file /tmp/.tmpUxFicl/agent-client-protocol-schema/src/rpc.rs:270
  struct agent_client_protocol_schema::ClientSide, previously in file /tmp/.tmpUxFicl/agent-client-protocol-schema/src/rpc.rs:179

--- failure trait_missing: pub trait removed or renamed ---

Description:
A publicly-visible trait cannot be imported by its prior path. A `pub use` may have been removed, or the trait itself may have been renamed or removed entirely.
        ref: https://doc.rust-lang.org/cargo/reference/semver.html#item-remove
       impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.46.0/src/lints/trait_missing.ron

Failed in:
  trait agent_client_protocol_schema::Side, previously in file /tmp/.tmpUxFicl/agent-client-protocol-schema/src/rpc.rs:146

Changelog

0.12.0 - 2026-04-17

Added

• (rust-only) Remove unused RPC message schema types (schema.json unchanged) (#1009)
• (rust-only) better tolerate malformed optional fields in deserialization (#1006)

Fixed

• (rpc) preserve '_' prefix for extension methods and reject empty ext (#883)

---

This PR was generated with release-plz.