Address code review: pin base image, pin Python 3.12, use python3 -m pip, add --frozen-lockfile

Co-authored-by: KSXGitHub <11488886+KSXGitHub@users.noreply.github.com>

Author: Copilot

.devcontainer/devcontainer.json

@@ -1,6 +1,6 @@
 {
   "name": "parallel-disk-usage",
-  "image": "mcr.microsoft.com/devcontainers/base:ubuntu",
+  "image": "mcr.microsoft.com/devcontainers/base:ubuntu-24.04",
   "features": {
     "ghcr.io/devcontainers/features/rust:1": {
       "version": "none",
@@ -11,7 +11,7 @@
       "nodeGypDependencies": true
     },
     "ghcr.io/devcontainers/features/python:1": {
-      "version": "latest",
+      "version": "3.12",
       "installTools": true
     },
     "ghcr.io/devcontainers-contrib/features/shellcheck:1": {},

.devcontainer/post-create.sh

@@ -2,11 +2,11 @@
 set -euo pipefail
 
 echo "Installing Python dependencies..." >&2
-pip install toml
+python3 -m pip install --user toml
 
 echo "Installing pnpm and project Node dependencies..." >&2
 npm install -g pnpm@7.33.7
-(cd ci/github-actions && pnpm install)
+(cd ci/github-actions && pnpm install --frozen-lockfile)
 
 echo "Installing hyperfine from GitHub release..." >&2
 hyperfine_version="1.20.0"