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.

.github/workflows/cargo-deny.yml

@@ -20,10 +20,10 @@ jobs:
           persist-credentials: false
 
       - name: Install Rust toolchain
-        uses: dtolnay/rust-toolchain@a0b273b48ed29de4470960879e8381ff45632f26 # 1.93.0
+        uses: dtolnay/rust-toolchain@e081816240890017053eacbb1bdf337761dc5582 # 1.95.0
 
       - name: Run cargo-deny
         uses: EmbarkStudios/cargo-deny-action@82eb9f621fbc699dd0918f3ea06864c14cc84246 # v2
         with:
-          rust-version: 1.93.0
+          rust-version: 1.95.0
           manifest-path: ./codex-rs/Cargo.toml