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/exec/src/lib.rs

@@ -2459,10 +2459,8 @@ fn decode_utf16(
         return Err(PromptDecodeError::InvalidUtf16 { encoding });
     }
 
-    let units: Vec<u16> = input
-        .chunks_exact(2)
-        .map(|chunk| decode_unit([chunk[0], chunk[1]]))
-        .collect();
+    let (units, _) = input.as_chunks();
+    let units: Vec<_> = units.iter().copied().map(decode_unit).collect();
 
     String::from_utf16(&units).map_err(|_| PromptDecodeError::InvalidUtf16 { encoding })
 }