refactor: slim flake.nix into nix/ entry files

nix/assets.nix

@@ -1,63 +0,0 @@
-{
-  stdenv,
-  librsvg,
-}:
-
-# Branding SVG/PNG family + claude prompts, split out from the rust
-# workspace so a tweak here doesn't invalidate the rust cargo cache.
-# Rationale + agent-configs PNG rendering: docs/gotchas.md::Split asset
-# derivations away from the rust workspace.
-#
-# Output layout:
-#   $out/share/hyperhive/branding/{hyperhive,agent-configs}.{svg,png}
-#   $out/share/hyperhive/prompts/{system.md, claude-settings.json}
-#
-# The repo docs/ tree is a SEPARATE derivation (nix/reference-docs.nix)
-# so agents can consume the docs without the branding+prompt assets and
-# the website repo can reuse it — see that file.
-
-stdenv.mkDerivation {
-  pname = "hyperhive-assets";
-  version = "0.1.0";
-  # Narrow `srcs` (branding/ + hive-ag3nt/prompts/) is what decouples
-  # this derivation's input hash from the rest of the tree.
-  srcs = [
-    ../branding
-    ../hive-ag3nt/prompts
-  ];
-  unpackPhase = ''
-    runHook preUnpack
-    cp -r ${../branding} branding
-    cp -r ${../hive-ag3nt/prompts} prompts
-    chmod -R u+w branding prompts
-    runHook postUnpack
-  '';
-
-  nativeBuildInputs = [ librsvg ];
-
-  # 300×300 matches branding/hyperhive.png — the size Forgejo's avatar
-  # endpoint accepts without resampling on upload.
-  buildPhase = ''
-    runHook preBuild
-    rsvg-convert --width 300 --height 300 \
-      -o branding/agent-configs.png \
-      branding/agent-configs.svg
-    runHook postBuild
-  '';
-
-  installPhase = ''
-    runHook preInstall
-    mkdir -p $out/share/hyperhive
-    cp -r branding $out/share/hyperhive/branding
-    cp -r prompts $out/share/hyperhive/prompts
-    runHook postInstall
-  '';
-
-  # Pure data — no executables to fixup, no shared libs to patchelf.
-  dontFixup = true;
-
-  meta = {
-    description = "hyperhive static assets (branding + claude prompts)";
-    homepage = "https://forge.darkest.space/hyperhive/hyperhive";
-  };
-}