chore: update devcontainer to python 3.13, ubuntu 24, and add fish shell

.devcontainer/devcontainer.json

@@ -3,12 +3,15 @@
 {
 	"name": "Ubuntu",
 	// Or use a Dockerfile or Docker Compose file. More info: https://containers.dev/guide/dockerfile
-	"image": "mcr.microsoft.com/devcontainers/base:jammy",
+	"image": "mcr.microsoft.com/devcontainers/base:noble",
 	// Features to add to the dev container. More info: https://containers.dev/features.
-	"features": {
-		"ghcr.io/devcontainers/features/github-cli:1": {},
-		"ghcr.io/devcontainers/features/python:1": {}
-	},
+        "features": {
+                "ghcr.io/devcontainers/features/github-cli:1": {},
+                "ghcr.io/devcontainers/features/python:1": {
+                        "version": "3.13"
+                },
+								"./features/fish": {}
+        },
 
 	// Use 'forwardPorts' to make a list of ports inside the container available locally.
 	// "forwardPorts": [],

.devcontainer/features/fish/devcontainer-feature.json

@@ -0,0 +1,10 @@
+{
+  "id": "fish",
+  "version": "1.0.0",
+  "name": "Fish shell",
+  "description": "Installs the fish shell from the Ubuntu package manager.",
+  "options": {},
+  "installsAfter": [
+    "ghcr.io/devcontainers/features/common-utils"
+  ]
+}

.devcontainer/features/fish/install.sh

@@ -0,0 +1,13 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+echo "Installing fish from distro package manager..."
+
+if command -v apt-get >/dev/null 2>&1; then
+    apt-get update
+    DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends fish
+    rm -rf /var/lib/apt/lists/*
+else
+    echo "Unsupported base image: expected apt-get (Ubuntu/Debian)." >&2
+    exit 1
+fi

.devcontainer/postCreateCommands.sh

@@ -1,10 +1,12 @@
-#/!bin/sh
+#!/bin/sh
+
+set -eu
 
 # Command to run during postCreateCommand
 # Done in script because when done via object the commands are run in parallel
 #  (which isn't always desirable)
 # https://containers.dev/implementors/spec/#parallel-exec
 # https://containers.dev/implementors/json_reference/#formatting-string-vs-array-properties
 
-pip install -r requirements.txt
+python3 -m pip install -r requirements.txt
 make html