Pin the Rust toolchain to 1.95.0 (#57373)

## What changed

- Replace Rust `1.99.1` pins with `1.95.0` across Cargo, Bazel, CI, release workflows, and Windows setup, and update the Bazel lockfile.
- Adjust Rust APIs, borrowing, and lint-related code for the pinned toolchain, and box MCP tool dispatch to bound compiler async-layout query depth.
- Update the halfwidth sound mark snapshot and allow optional symbol hash suffixes in the code mode host package smoke test.

GitOrigin-RevId: 75460c3d0465dc601811e619bce373a4f7ff2912

codex-rs/diagnostics/src/lib.rs

@@ -32,7 +32,7 @@ impl Gauge {
     pub fn decrement(&self) {
         let _ = self
             .value
-            .try_update(Ordering::Relaxed, Ordering::Relaxed, |value| {
+            .fetch_update(Ordering::Relaxed, Ordering::Relaxed, |value| {
                 Some(value.saturating_sub(1))
             });
     }