Add new packages and build scripts for various libraries

- Added Nuklear GUI library with build script and configuration.
- Introduced OpenH264 encoder/decoder with build configuration.
- Added PortAudio library for audio I/O with custom build script.
- Included Python Execnet for multi-Python deployment.
- Added Pytest Xdist plugin for distributed testing.
- Introduced Shaderc for shader compilation tools.
- Added Snappy compression library with necessary patches and configuration.
- Included SoundTouch audio processing library with build configuration.
- Added SRT library for secure reliable transport.
- Introduced VapourSynth video processing framework with configuration.
- Added Vid.stab for video stabilization.
- Included WebRTC Audio Processing library with build configuration.
- Added X264 video encoding library with patches for POSIX compliance.
- Introduced X265 video encoder with build configuration.
- Added XKeyboard Config for X keyboard configuration files.
- Included Xorg XKBComp for keyboard description compilation.
- Added Xvidcore MPEG-4 video codec library with configuration.
- Introduced ZeroMQ messaging system with patches and build configuration.
- Added Zimg library for scaling and colorspace conversion.

extra/x264/x264.toml

@@ -0,0 +1,33 @@
+[build]
+type = "autotools"
+
+[build.flags]
+configure = [
+    "--enable-shared",
+    "--disable-cli",
+    "--enable-pic",
+    "--disable-avs",
+]
+
+[dependencies]
+build = ["nasm"]
+runtime = [
+    "glibc",
+    "l-smash",
+]
+
+[package]
+description = "a library for encoding video streams into the H.264/MPEG-4 AVC format"
+homepage = "https://www.videolan.org/developers/x264.html"
+license = "GPL-2.0-only"
+name = "x264"
+version = "20250815"
+
+[[source]]
+extract_dir = "$name-$version"
+sha256 = "eb9c8febcf4889d01a4fd97f67a9bec74981a67c89d04e492b74e81edd720031"
+url = "https://anduin.linuxfromscratch.org/BLFS/x264/x264-$version.tar.xz"
+patches = [ "x264-posixify.patch" ]
+
+[[manual_sources]]
+file = "x264-posixify.patch"