Upgrade the Rust toolchain to 1.99.1 (#61205)

## What changed

- Update the workspace, Bazel toolchain and lockfile, CI and release workflows, and Windows setup script from Rust `1.95.0` to `1.99.1`.
- Adapt Rust code to the updated toolchain and Clippy lints, including `try_update` for atomics, `as_chunks` for fixed-size slices, and targeted allowances for generated tonic services.
- Refresh the halfwidth sound mark rendering snapshot to use literal characters in debug output.

GitOrigin-RevId: 5852029f687436dc814c2bca68141ee1f4a67d49

codex-rs/external-agent-migration/src/mcp.rs

@@ -222,7 +222,8 @@ fn mcp_server_toml_table(
         if let Some(env) = server_config.get("env").and_then(JsonValue::as_object) {
             append_env_config(&mut table, env)?;
         }
-    } else if let Some(url) = server_config.get("url").and_then(json_string) {
+    } else {
+        let url = server_config.get("url").and_then(json_string)?;
         if !matches!(
             transport_type,
             None | Some("http") | Some("streamable_http")
@@ -236,8 +237,6 @@ fn mcp_server_toml_table(
         if let Some(headers) = server_config.get("headers").and_then(JsonValue::as_object) {
             append_header_config(&mut table, headers)?;
         }
-    } else {
-        return None;
     }
 
     Some(table)