fix(install): chown the generated flake to the user; harden HM pre-activation

End-to-end VM verification found the installed system perfect (LUKS,
auto-login, swapfile+resume, snapper) except: ~/.nomarchy was root-owned,
so libgit2 refused every `home-manager switch` ("repository not owned by
current user"). chown 1000:users after generation (the account doesn't
exist in the target yet — numeric ids).

The chroot pre-activation now builds via path: instead of git+file —
no libgit2, no ownership sensitivity — and the fallback message suggests
-b bak (a default-config Hyprland session leaves an autogenerated
hyprland.conf in the way otherwise; observed live).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

pkgs/nomarchy-install/nomarchy-install.sh

@@ -405,6 +405,12 @@ fi
         commit -qm "Initial Nomarchy configuration"
 )
 
+# The user must own their flake — libgit2 refuses repositories owned by
+# someone else, which breaks `home-manager switch` (and theme switching)
+# outright. The first normal NixOS user is always 1000:users(100); the
+# account doesn't exist in the target yet, so numeric ids it is.
+chown -R 1000:100 "$FLAKE_DIR"
+
 # /etc/nixos on the installed system points at the user-owned flake.
 mkdir -p /mnt/etc
 ln -sfn "/home/$USERNAME/.nomarchy" /mnt/etc/nixos
@@ -463,7 +469,7 @@ export NIX_CONFIG=$(printf '%q' "$NIX_CONFIG")
 out=\$(nix --extra-experimental-features "nix-command flakes" \
     build --no-link --print-out-paths \
     --option substituters "" \
-    "/home/$USERNAME/.nomarchy#homeConfigurations.$USERNAME.activationPackage")
+    "path:/home/$USERNAME/.nomarchy#homeConfigurations.$USERNAME.activationPackage")
 install -d -o "$USERNAME" -g users /nix/var/nix/profiles/per-user/$USERNAME
 install -d -o "$USERNAME" -g users /nix/var/nix/gcroots/per-user/$USERNAME
 runuser -u "$USERNAME" -- bash -lc "USER=$USERNAME HOME=/home/$USERNAME \$out/activate"
@@ -472,7 +478,7 @@ if nixos-enter --root /mnt -- bash /tmp/nomarchy-hm-activate.sh; then
     success "Desktop pre-activated — first boot is fully themed"
 else
     warn "Desktop pre-activation failed; after first login run:"
-    warn "  home-manager switch --flake ~/.nomarchy"
+    warn "  home-manager switch --flake ~/.nomarchy -b bak"
 fi
 rm -f /mnt/tmp/nomarchy-hm-activate.sh