Uprev Rust toolchain pins to 1.95.0 (#24684)

## Summary
- Bump the workspace Rust toolchain from `1.93.0` to `1.95.0` across
Cargo, Bazel, CI, release workflows, devcontainers, and the Codex
environment config.
- Refresh `MODULE.bazel.lock` so the Bazel Rust toolchain artifacts
match the new version.
- Leave purpose-specific toolchains unchanged, including the
`argument-comment-lint` nightly and the upstream `rusty_v8` `1.91.0`
build pin.
- Includes fixes for new lints from `just fix` and a few codex-authored
fixes for lints without a suggestion.

codex-rs/cli/src/doctor.rs

@@ -2176,11 +2176,7 @@ struct RolloutStats {
 
 impl RolloutStats {
     fn average_bytes(&self) -> u64 {
-        if self.files == 0 {
-            0
-        } else {
-            self.total_bytes / self.files
-        }
+        self.total_bytes.checked_div(self.files).unwrap_or(0)
     }
 }