chore: delete orphan config assets + log chromium/templates concerns

Two unreferenced asset files removed; two larger concerns deferred to
roadmap rows because they need more thought than a focused audit
allows.

Deleted:
- `features/apps/alacritty/config/alacritty.toml` — the alacritty
  module uses `programs.alacritty.settings` (Nix attrset) exclusively;
  nothing references the on-disk file. The neighbouring (already-empty)
  `themes/` directory goes with it.
- `themes/templates/mako.ini.tpl` — no script reads it.

Deferred to ROADMAP "Later":
- `features/apps/chromium/Default/Preferences` is deployed as a Home
  Manager symlink into chromium's mutable profile directory. Either
  silently replaced on first save or silently failing to write —
  either way the static defaults don't survive. The actual chromium
  theming work happens via managed policies in
  core/system/browser.nix. Needs chromium-internals knowledge to
  decide whether to remove or rework, so flagged rather than
  unilaterally deleted.
- `themes/templates/*.tpl` (the remaining 10 templates) are also
  apparently orphan — deployed via xdg.dataFile but unconsumed by any
  script. Likely vestigial from a pre-stylix templating system.
  Logged as a separate row to decide deletion vs documentation as
  user-reference assets.

Found during Pillar 8 audit of features/apps.

docs/ROADMAP.md

@@ -41,6 +41,8 @@ Guardrails (apply when adding anything):
 - **Optional `nomarchy-installer-vm`** rebuilt as a real flake app (not a one-off shell script) so users can install Nomarchy into a libvirt VM declaratively.
 - **Surface support module** via the relevant `nixos-hardware` profile + Surface kernel patches behind a `nomarchy.hardware.isSurface` toggle.
 - **Consolidate palette imports in `flake.nix` via `nomarchyLib`.** `flake.nix:79-80` re-imports `./themes/palettes` and recomputes `themeNames` even though `lib/default.nix` already exports both. Two computations, same result today — drift risk tomorrow. Import `nomarchyLib = import ./lib { inherit lib; }` once and use `nomarchyLib.{palettes,themeNames}` to make `lib/default.nix` the single source of truth for the theme list.
+- **Decide what to do about `features/apps/chromium/Default/Preferences`.** The module deploys a static 204-byte `Default/Preferences` (setting `extensions.theme.use_system = false`, `browser.theme.color_scheme = 2`) into chromium's mutable profile directory via Home Manager symlink. Chromium expects to write that file at runtime, so either the symlink is silently replaced on first save (losing the static defaults) or the write fails silently. The real chromium theming work happens via managed policies in `core/system/browser.nix`. Probably the user-profile deployment should be removed; needs someone with chromium-internals knowledge to confirm before deletion.
+- **`themes/templates/*.tpl` — decide what these are for.** Eleven mustache-style templates (`alacritty.toml.tpl`, `btop.theme.tpl`, `kitty.conf.tpl`, etc.) are deployed to `~/.local/share/nomarchy/templates/` via `themes/engine/files.nix`, but no script in the tree consumes them. Likely vestigial from a pre-stylix templating system. Either delete the directory + the `xdg.dataFile` deployment, or document them as user-reference assets and explain how to use them.
 
 ## 3. Pillar: Script & menu audit
 

features/apps/alacritty/config/alacritty.toml

@@ -1,25 +0,0 @@
-general.import = [ "~/.config/nomarchy/current/theme/alacritty.toml" ]
-
-[env]
-TERM = "xterm-256color"
-
-[terminal]
-osc52 = "CopyPaste"
-
-[font]
-normal = { family = "JetBrainsMono Nerd Font", style = "Regular" }
-bold = { family = "JetBrainsMono Nerd Font", style = "Bold" }
-italic = { family = "JetBrainsMono Nerd Font", style = "Italic" }
-size = 9
-
-[window]
-padding.x = 14
-padding.y = 14
-decorations = "None"
-
-[keyboard]
-bindings = [
-{ key = "Insert", mods = "Shift", action = "Paste" },
-{ key = "Insert", mods = "Control", action = "Copy" },
-{ key = "Return", mods = "Shift", chars = "\u001B\r" }
-]

themes/templates/mako.ini.tpl

@@ -1,5 +0,0 @@
-include=~/.config/nomarchy/default/mako/core.ini
-
-text-color={{ foreground }}
-border-color={{ accent }}
-background-color={{ background }}