fix: trim MCP tool names to fit into tool name length limit (#1571)

Store fully qualified names along with tool entries so we don't have to re-parse them.

Fixes: https://github.com/openai/codex/issues/1289

codex-rs/core/Cargo.toml

@@ -28,6 +28,7 @@ rand = "0.9"
 reqwest = { version = "0.12", features = ["json", "stream"] }
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
+sha1 = "0.10.6"
 strum_macros = "0.27.1"
 thiserror = "2.0.12"
 time = { version = "0.3", features = ["formatting", "local-offset", "macros"] }