feat(install): copy templates/downstream and patch install values

Make the downstream template the single source of truth for machine
flakes: nomarchy-install copies flake/system/home/theme-state and
patch-template.py only fills hostname, user, keyboard, detected
hardware, snapper, resume, and password. Install and flake-init users
now share the same commented opt-ins and starter home.packages.

Also: BACKLOG boreal-as-default proposal; installer audit notes;
HARDWARE.md from prior work if uncommitted.

README.md

@@ -73,7 +73,7 @@ Flat on purpose. Two module trees, one options file each, no hidden layers.
 ├── pkgs/
 │   ├── nomarchy-theme-sync/       # state writer + rebuild dispatcher (Python)
 │   └── nomarchy-install/          # live-ISO installer (gum + disko + mkFlake)
-├── templates/downstream/          # `nix flake init -t` starter for users
+├── templates/downstream/          # machine flake SoT (`flake init` + installer copy/patch)
 ├── docs/TESTING.md                # how to verify changes (incl. AI-agent rules)
 ├── docs/HARDWARE.md               # firmware, drivers, profiles, unsupported machines
 ├── docs/OVERRIDES.md              # how downstream users override defaults