Housekeeping - documentation update.

Introduced a new dependency checking script that validates required apt packages before building the project

Documented the expanded package list and instructions for running the script within the build prerequisites documentation

Updated build system instructions to call the dependency checker prior to configuring with CMake

scripts/check_deps.sh

@@ -0,0 +1,30 @@
+#!/usr/bin/env bash
+# Check for required system packages for building PiPedal.
+
+set -e
+
+packages=(\
+    liblilv-dev libboost-dev libsystemd-dev catch libasound2-dev uuid-dev \
+    authbind libavahi-client-dev libnm-dev libicu-dev \
+    libsdbus-c++-dev libzip-dev google-perftools \
+    libgoogle-perftools-dev libpipewire-0.3-dev \
+    libwebsocketpp-dev libsdl2-dev
+)
+
+missing=()
+
+for pkg in "${packages[@]}"; do
+    if ! dpkg -s "$pkg" >/dev/null 2>&1; then
+        missing+=("$pkg")
+    fi
+done
+
+if [ ${#missing[@]} -ne 0 ]; then
+    echo "Missing packages:" >&2
+    for pkg in "${missing[@]}"; do
+        echo "  $pkg" >&2
+    done
+    exit 1
+else
+    echo "All required packages are installed." >&2
+fi