refactor: change to litterate config

Configuration is now held by the `.org` files. All `.nix` files are
tangled from the org-mode files.

packages/bun-baseline.nix

@@ -1,7 +1,3 @@
-# Baseline variant of Bun for x86_64-linux CPUs without AVX2 support.
-# The regular `bun` from nixpkgs requires AVX2 and crashes with SIGILL on older hardware.
-#
-# Version is typically kept in sync with nixpkgs's `bun` (passed via `callPackage`).
 {
   lib,
   stdenvNoCC,
@@ -13,8 +9,6 @@
   stdenv,
   version ? "1.3.13",
 }: let
-  # When updating `version`, compute the new hash with:
-  #   nix store prefetch-file  "https://github.com/oven-sh/bun/releases/download/bun-v${version}/bun-linux-x64-baseline.zip"
   hash = {
     "1.3.13" = "sha256-nYokKSpwaAkCBdqsCloiP19pc29Sh+N7+I07QDHtx1A=";
   };

packages/cairn.nix

@@ -0,0 +1,88 @@
+# https://cairns.gg/
+{
+  stdenv,
+  fetchzip,
+  makeWrapper,
+  lib,
+  fontconfig,
+  freetype,
+  libx11,
+  libxext,
+  libxrandr,
+  libxinerama,
+  libxi,
+  libxcursor,
+  libxrender,
+  libxfixes,
+  libxtst,
+  libxcb,
+  libxkbcommon,
+  libglvnd,
+  libICE,
+  libSM,
+  dbus,
+  libxshmfence,
+}:
+stdenv.mkDerivation rec {
+  pname = "cairn";
+  version = "0.9.11";
+  src = fetchzip {
+    url = "https://download.cairns.gg/releases/${version}/${pname}-${version}-linux-x64.tar.gz";
+    hash = "sha256-UbjeEbP4o6y+0j1oeF3RwqTuunGB5wD0CSpdFDk97/U=";
+  };
+
+  nativeBuildInputs = [makeWrapper];
+
+  dontBuild = true;
+  dontPatchELF = true;
+  dontStrip = true;
+
+  installPhase = ''
+    runHook preInstall
+    install -Dm755 $src/cairn $out/bin/cairn
+    wrapProgram $out/bin/cairn \
+      --prefix LD_LIBRARY_PATH : ${lib.makeLibraryPath [
+      stdenv.cc.cc.lib
+      fontconfig
+      freetype
+      libx11
+      libxext
+      libxrandr
+      libxinerama
+      libxi
+      libxcursor
+      libxrender
+      libxfixes
+      libxtst
+      libxcb
+      libxkbcommon
+      libglvnd
+      libICE
+      libSM
+      dbus
+      libxshmfence
+    ]}
+
+    mkdir -p $out/share/applications
+    cat > $out/share/applications/cairn.desktop <<EOF
+[Desktop Entry]
+Version=0.9.11
+Name=Cairns
+Comment=Modpacks for Vintage Story
+Exec=$out/bin/cairn
+Icon=cairn
+Terminal=false
+Type=Application
+Categories=Games
+EOF
+
+    install -Dm644 ${./cairn.svg} $out/share/icons/hicolor/scalable/apps/${pname}.svg
+    runHook postInstall
+  '';
+
+  meta = {
+    description = "Modpacks for Vintage Story";
+    homepage = "https://cairns.gg/";
+    platforms = ["x86_64-linux"];
+  };
+}

packages/cairn.svg

@@ -0,0 +1,73 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="1024" height="1024" viewBox="0 0 1024 1024">
+  <!--
+    Cairn: the stack of stones you build so you can find the exact way back.
+
+    Palette is the game's own Vintagestory.API.Client.GuiStyle, the same source the
+    launcher's theme draws from, so the icon sits next to the app rather than merely
+    near it. Stones lighten as they rise and the cap is ColorRust1 — the accent already
+    carried by the Play button and the selected tab.
+
+    Constraint that drove the shapes: this has to survive 16x16 in a Windows taskbar.
+    So the silhouette does the work — a clear taper, five stones, dark gaps wide enough
+    to still separate them when each is barely two pixels tall. Detail is layered on
+    top for the sizes that can show it, and is expendable below them.
+  -->
+  <defs>
+    <linearGradient id="bg" x1="0" y1="0" x2="0" y2="1">
+      <stop offset="0" stop-color="#37291F"/>
+      <stop offset="1" stop-color="#191210"/>
+    </linearGradient>
+
+    <radialGradient id="glow" cx="0.5" cy="0.60" r="0.58">
+      <stop offset="0" stop-color="#C89A5E" stop-opacity="0.26"/>
+      <stop offset="1" stop-color="#C89A5E" stop-opacity="0"/>
+    </radialGradient>
+
+    <linearGradient id="s1" x1="0.15" y1="0" x2="0.6" y2="1">
+      <stop offset="0" stop-color="#D3B78C"/><stop offset="1" stop-color="#836A4E"/>
+    </linearGradient>
+    <linearGradient id="s2" x1="0.15" y1="0" x2="0.6" y2="1">
+      <stop offset="0" stop-color="#DFC393"/><stop offset="1" stop-color="#927A58"/>
+    </linearGradient>
+    <linearGradient id="s3" x1="0.15" y1="0" x2="0.6" y2="1">
+      <stop offset="0" stop-color="#E9CD9B"/><stop offset="1" stop-color="#A28560"/>
+    </linearGradient>
+    <linearGradient id="s4" x1="0.15" y1="0" x2="0.6" y2="1">
+      <stop offset="0" stop-color="#F3D6A2"/><stop offset="1" stop-color="#B0906A"/>
+    </linearGradient>
+    <linearGradient id="s5" x1="0.15" y1="0" x2="0.6" y2="1">
+      <stop offset="0" stop-color="#F0801F"/><stop offset="1" stop-color="#9C4108"/>
+    </linearGradient>
+  </defs>
+
+  <rect width="1024" height="1024" rx="228" fill="url(#bg)"/>
+  <rect width="1024" height="1024" rx="228" fill="url(#glow)"/>
+
+  <!-- Grounds the stack without committing to a horizon line. -->
+  <ellipse cx="512" cy="880" rx="322" ry="27" fill="#0F0B09" opacity="0.5"/>
+
+  <!--
+    Each stone is tilted a few degrees, and no two share a width-to-height ratio, so the
+    stack looks built by hand rather than turned on a lathe. The dark outline is what
+    keeps the gaps legible once antialiasing starts merging neighbours.
+  -->
+  <g stroke="#171110" stroke-width="8">
+    <ellipse cx="512" cy="788" rx="286" ry="84" fill="url(#s1)" transform="rotate(-2.5 512 788)"/>
+    <ellipse cx="490" cy="612" rx="236" ry="74" fill="url(#s2)" transform="rotate(3.5 490 612)"/>
+    <ellipse cx="532" cy="458" rx="190" ry="68" fill="url(#s3)" transform="rotate(-4.5 532 458)"/>
+    <ellipse cx="498" cy="322" rx="146" ry="53" fill="url(#s4)" transform="rotate(6 498 322)"/>
+    <ellipse cx="520" cy="204" rx="103" ry="46" fill="url(#s5)" transform="rotate(-4 520 204)"/>
+  </g>
+
+  <!--
+    Top-lit highlights: they give the stones volume at 128px and up, and simply dissolve
+    into the fill below that, which is the correct behaviour for detail this fine.
+  -->
+  <g fill="#FFFFFF" opacity="0.20">
+    <ellipse cx="470" cy="748" rx="150" ry="26" transform="rotate(-2.5 470 748)"/>
+    <ellipse cx="452" cy="578" rx="124" ry="23" transform="rotate(3.5 452 578)"/>
+    <ellipse cx="498" cy="428" rx="100" ry="21" transform="rotate(-4.5 498 428)"/>
+    <ellipse cx="470" cy="299" rx="76"  ry="16" transform="rotate(6 470 299)"/>
+    <ellipse cx="498" cy="184" rx="54"  ry="14" transform="rotate(-4 498 184)"/>
+  </g>
+</svg>