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/utils/path-uri/src/api_path_string.rs

@@ -263,9 +263,7 @@ fn render_windows_opaque_fallback(path_bytes: &[u8]) -> Option<String> {
         return None;
     }
     let path_wide = path_bytes
-        .as_chunks::<2>()
-        .0
-        .iter()
+        .chunks_exact(2)
         .map(|bytes| u16::from_le_bytes([bytes[0], bytes[1]]))
         .collect::<Vec<_>>();
 

codex-rs/utils/path-uri/src/lib.rs

@@ -587,11 +587,8 @@ impl PathUri {
                 use std::os::windows::ffi::OsStringExt;
                 path_bytes.len().is_multiple_of(2).then(|| {
                     let path_wide = path_bytes
-                        .as_chunks::<2>()
-                        .0
-                        .iter()
-                        .copied()
-                        .map(u16::from_le_bytes)
+                        .chunks_exact(2)
+                        .map(|bytes| u16::from_le_bytes([bytes[0], bytes[1]]))
                         .collect::<Vec<_>>();
                     std::path::PathBuf::from(std::ffi::OsString::from_wide(&path_wide))
                 })
@@ -822,9 +819,7 @@ fn infer_opaque_path_convention(path_bytes: &[u8]) -> Option<PathConvention> {
     }
 
     let mut path_wide = path_bytes
-        .as_chunks::<2>()
-        .0
-        .iter()
+        .chunks_exact(2)
         .map(|bytes| u16::from_le_bytes([bytes[0], bytes[1]]));
     let first = path_wide.next()?;
     let second = path_wide.next()?;

codex-rs/utils/stream-parser/src/inline_hidden_tag.rs

@@ -92,7 +92,7 @@ where
             .iter()
             .map(|spec| longest_suffix_prefix_len(pending, spec.open))
             .max()
-            .unwrap_or(0)
+            .map_or(0, std::convert::identity)
     }
 
     fn push_visible_prefix(out: &mut StreamTextChunk<ExtractedInlineTag<T>>, pending: &str) {