fix(distro): fix /etc/nixos ownership, theme discovery, and CLI wrappers

- installer: set recursive ownership of /etc/nixos to main user post-install
- themes: fix NOMARCHY_PATH and discovery logic for Lua theme menu
- scripts: update CLI wrappers (font, theme, wallpaper) to use Walker menus
- core: remove obsolete NOMARCHY_PATH and cleanup dead code
- features: add pkgs.lua for Walker and remove obsolete switcher.nix
- docs: update ROADMAP.md, SCRIPTS.md and STRUCTURE.md

docs/ROADMAP.md

@@ -136,6 +136,8 @@ Nomarchy is moving away from being a "flavor" of Omarchy to its own distinct ide
 
 (Move items here when they land — keep them brief, link the commit/PR.)
 
+- _2026-05-03_ — Fixed CLI wrappers and removed obsolete code. (1) Updated `nomarchy-font`, `nomarchy-theme`, and `nomarchy-wallpaper` CLI wrappers to use modern Walker menus; (2) Removed the obsolete and broken `themes/engine/switcher.nix` and its associated Nix-inlined scripts; (3) Cleaned up remaining `$NOMARCHY_PATH` references from the Omarchy era.
+- _2026-05-03_ — Fixed `/etc/nixos` ownership after installation. Added a `chown -R $USERNAME:users /etc/nixos` step via `nixos-enter` at the end of `installer/install.sh` so the main user owns their configuration and can run `home-manager` commands without `sudo`.
 - _2026-05-01_ — Installer & Script Audit Polish. (1) Fixed a critical bash dynamic scoping bug in `installer/install.sh` where `rc=0` assignments inside functions (Impermanence, Form Factor) were clobbering the main loop's return code, causing the installer to abort when "No" was selected; (2) Polished `hosts/nomarchy-live.nix` with auto-login for the `nixos` user and passwordless sudo for the `wheel` group; (3) Repurposed `nomarchy-toggle-suspend` to execute `systemctl suspend` directly and updated `nomarchy-menu` to reflect this; (4) Updated `nomarchy-launch-wifi` to use `nmtui` in Alacritty; (5) Regenerated `docs/SCRIPTS.md` to reflect the updated script mappings.
 - _2026-04-30_ — `set -e` sweep across `nomarchy-*` scripts. Added `set -e` to 142 of 169 bash scripts that lacked it (27 already had it). Halts a class of "command failed silently in the middle of a chain, system left in half-applied state" bugs that produced repeat-fix commits. One deliberate exception: `nomarchy-menu` runs without `set -e` because it's an interactive UX loop where action failures should re-display the menu rather than abort the script. Pre-commit hook now enforces `bash -n` + `shellcheck --severity=error` so future scripts can't regress this.
 - _2026-04-30_ — Installer disk-phase reliability. Hardened `installer/install.sh` and consolidated the disko configs: (1) `select_disk` now hides the live-ISO boot device(s) so the installer can't format its own boot media (`NOMARCHY_INSTALL_ALLOW_ISO_TARGET=1` to override); (2) added a 10 GiB minimum-capacity preflight; (3) `prewipe_target_drive` enumerates every active dm-crypt mapping backed by the target drive and closes them, drops the silent `|| true` from `wipefs`/`sgdisk`/`dd`, bounds `udevadm settle` to 30s, and refuses to continue if anything is still mounted; (4) wrapped the disko call in `run_disko_with_retry` with last-30-lines + Retry / View full log / Abort dialog on failure; (5) replaced the sed-templated `disko-golden.nix` + `disko-btrfs-multi.nix` pair with a single `disko-config.nix` Nix function called via `--argstr mainDrive … --arg extraDrives '[…]'` — eliminates a class of escaping bugs (cf. `3aadc36`); (6) added an EXIT trap so the tmpfs LUKS key file is removed even on early abort.