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

.github/workflows/rust-release-windows.yml

@@ -106,7 +106,7 @@ jobs:
           Write-Host "Disk usage:"
           Get-PSDrive -PSProvider FileSystem | Format-Table -AutoSize Name, @{Name='Size(GB)';Expression={[math]::Round(($_.Used + $_.Free) / 1GB, 1)}}, @{Name='Free(GB)';Expression={[math]::Round($_.Free / 1GB, 1)}}
       - name: Set up Rust toolchain
-        uses: dtolnay/rust-toolchain@e081816240890017053eacbb1bdf337761dc5582 # 1.95.0
+        uses: dtolnay/rust-toolchain@d124f86f28ff42855784ff3319f48ac182c248f8 # 1.99.1
         with:
           targets: ${{ matrix.build-system == 'cargo' && matrix.target || '' }}