fix(install): bake dconf, seed main, name ISO, display modes (#123–#126)

Batch of existing-bug fixes from Acer/XPS install findings:

- #123: HM pre-activate creates /run/user/$UID and prefers
  dbus-run-session so dconf no longer aborts the desktop bake
- #124: main-built ISOs seed ?ref=main; patch-template rewrites
  inputs.nomarchy.url from NOMARCHY_FLAKE_URL (was set but unused)
- #125: image.baseName → nomarchy-live-….iso (not nixos-live-…)
- #126: Display mode list sorted by pixel area; toast shows hyprctl
  size; TESTING notes QEMU fixed-window scaling illusion

Verified: V0 flake check, installer-safety, baseName eval, patch-template
flakeUrl rewrite, mode-sort fixture.

pkgs/nomarchy-install/nomarchy-install.sh

@@ -621,7 +621,8 @@ python3 "$SHARE/patch-template.py" "$FLAKE_DIR" <<PYJSON
     "npu": $(if [[ -n "$NPU_VENDOR" ]]; then printf '%s' "$NPU_VENDOR" | python3 -c 'import json,sys; print(json.dumps(sys.stdin.read().rstrip("\n")))'; else echo null; fi)
   },
   "resumeOffset": $resume_json,
-  "rootUuid": $root_uuid_json
+  "rootUuid": $root_uuid_json,
+  "flakeUrl": $(printf '%s' "${NOMARCHY_FLAKE_URL:?NOMARCHY_FLAKE_URL unset}" | python3 -c 'import json,sys; print(json.dumps(sys.stdin.read().rstrip("\n")))')
 }
 PYJSON
 
@@ -771,10 +772,28 @@ nix-daemon &
 daemon_pid=\$!
 trap 'kill \$daemon_pid 2>/dev/null || true' EXIT
 sleep 2
+# Pre-activate has no graphical session: without XDG_RUNTIME_DIR, HM's
+# dconfSettings step dies ("Unable to create directory /run/user/UID/dconf:
+# Permission denied") and the rest of activation never runs — first boot
+# then lands half-themed (#123). Create a private runtime dir the target
+# user owns, and wrap activate in a session bus (dconf needs one).
+uid=$USER_UID
+install -d -o "$USERNAME" -g users -m 700 "/run/user/\$uid"
 # BACKUP_EXT: collisions can't abort the activation (a stray
 # autogenerated config gets moved aside instead).
-runuser -u "$USERNAME" -- bash -lc \
-    "USER=$USERNAME HOME=/home/$USERNAME NIX_REMOTE=daemon HOME_MANAGER_BACKUP_EXT=bak \$out/activate"
+if command -v dbus-run-session >/dev/null 2>&1; then
+  runuser -u "$USERNAME" -- env \
+    USER="$USERNAME" HOME="/home/$USERNAME" \
+    XDG_RUNTIME_DIR="/run/user/\$uid" \
+    NIX_REMOTE=daemon HOME_MANAGER_BACKUP_EXT=bak \
+    dbus-run-session -- "\$out/activate"
+else
+  runuser -u "$USERNAME" -- env \
+    USER="$USERNAME" HOME="/home/$USERNAME" \
+    XDG_RUNTIME_DIR="/run/user/\$uid" \
+    NIX_REMOTE=daemon HOME_MANAGER_BACKUP_EXT=bak \
+    "\$out/activate"
+fi
 EOF
 # NOMARCHY_TEST_FORCE_HM_FAIL=1 — unattended harness only (#54 V2): take
 # the failure arm so the durable recovery hint is exercised without a