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.

.devcontainer/devcontainer.secure.json

@@ -7,7 +7,7 @@
     "args": {
       "TZ": "${localEnv:TZ:UTC}",
       "NODE_MAJOR": "22",
-      "RUST_TOOLCHAIN": "1.92.0",
+      "RUST_TOOLCHAIN": "1.95.0",
       "CODEX_NPM_VERSION": "0.121.0"
     }
   },