refactor: nix/host-modules + nix/agent-modules layout, update doc paths

nix/host-modules/hive-c0re/theme.nix

@@ -0,0 +1,79 @@
+# Stylix theme integration (zero-op auto-detect). When the operator's
+# host config has stylix enabled, generate a base16 `colors.css` from
+# its palette and overlay it onto the bundled frontend dist so the
+# dashboard re-themes with no operator action and no npm/esbuild
+# rebuild (a pure file-copy over the prebuilt dist). `colors.css` is
+# the entire swap contract — `theme.css` derives every semantic var
+# from the 16 base16 slots (see docs/web-ui/css-vars.md). The guarded
+# access makes this a clean no-op when stylix isn't imported into the
+# host config. Exposed as the read-only `c0re.servedFrontend` option.
+{
+  pkgs,
+  lib,
+  config,
+  ...
+}:
+let
+  cfg = config.services.hyperhive.c0re;
+  stylixThemeColors =
+    if (config.stylix.enable or false) && ((config.lib.stylix or { }) ? colors) then
+      config.lib.stylix.colors.withHashtag
+    else
+      null;
+  themedColorsCss =
+    c:
+    pkgs.writeText "hyperhive-colors.css" ''
+      :root {
+        --base00: ${c.base00};
+        --base01: ${c.base01};
+        --base02: ${c.base02};
+        --base03: ${c.base03};
+        --base04: ${c.base04};
+        --base05: ${c.base05};
+        --base06: ${c.base06};
+        --base07: ${c.base07};
+        --base08: ${c.base08};
+        --base09: ${c.base09};
+        --base0A: ${c.base0A};
+        --base0B: ${c.base0B};
+        --base0C: ${c.base0C};
+        --base0D: ${c.base0D};
+        --base0E: ${c.base0E};
+        --base0F: ${c.base0F};
+      }
+    '';
+  # Overlay the generated colors.css onto both dist subtrees. Both the
+  # dashboard (served by hive-c0re via HIVE_STATIC_DIR) and the agent UIs
+  # (served by the gateway from HIVE_AGENT_FRONTEND_DIR — static files
+  # straight from the store) read their colors.css from this host-side
+  # tree, so swapping both re-themes both surfaces.
+  #
+  # Not covered here: an agent reached directly on its own harness web
+  # server (no gateway) serves from its per-agent `mergedDist`, built in
+  # the agent's own nixosSystem with no access to the host's stylix
+  # colours — theming that path needs the base16 palette forwarded
+  # host→agent, tracked separately.
+  themedFrontend =
+    c:
+    pkgs.runCommand "hyperhive-frontend-themed" { } ''
+      cp -r ${cfg.frontend} $out
+      chmod -R u+w $out
+      install -m644 ${themedColorsCss c} $out/dashboard/static/colors.css
+      install -m644 ${themedColorsCss c} $out/agent/static/colors.css
+    '';
+in
+{
+  options.services.hyperhive.c0re.servedFrontend = lib.mkOption {
+    type = lib.types.package;
+    internal = true;
+    readOnly = true;
+    default = if stylixThemeColors != null then themedFrontend stylixThemeColors else cfg.frontend;
+    defaultText = lib.literalExpression "<stylix-themed overlay of `frontend`>";
+    description = ''
+      Internal, read-only: `frontend` re-themed with the active stylix
+      palette (or `frontend` verbatim when unthemed); has `dashboard/`
+      and `agent/`. Exposed so the hive-gateway module can static-serve
+      `dashboard/` as an nginx root instead of proxying to hive-c0re.
+    '';
+  };
+}