feat(install): #61 review Source line tracks offline/online

Gate the Review panel Source wording on the same OFFLINE flag as the
cache.nixos.org probe (ISO-only vs may use network binary caches).
Extend installer-safety pure contract so both phrases and $SOURCE_NET
cannot regress.

Also promote Bernardo-accepted A/B/C batch → NEXT #55–#63 and close #61.

Verified: V0 (check-install-safety + bash -n + checks.installer-safety).

pkgs/nomarchy-install/nomarchy-install.sh

@@ -276,6 +276,14 @@ info "Profiles: ${HW_PROFILES[*]:-(none)}"
 # ─── Review & point of no return ────────────────────────────────────────
 section "Review"
 
+# Match the Source line to the same cache.nixos.org probe that sets OFFLINE
+# (above): offline = ISO store only; online may still hit substituters.
+if [[ "$OFFLINE" == true ]]; then
+    SOURCE_NET="pinned into the ISO, no network needed"
+else
+    SOURCE_NET="pinned into the ISO; may use network binary caches"
+fi
+
 gum style --border normal --padding "0 2" \
     "Disk:       $TARGET_DISK  (WILL BE ERASED)" \
     "Encryption: $([[ $WITH_LUKS == true ]] && echo "LUKS2 + desktop auto-login" || echo none)" \
@@ -285,7 +293,7 @@ gum style --border normal --padding "0 2" \
     "Timezone:   $TIMEZONE" \
     "Hardware:   ${HW_PROFILES[*]:-none}" \
     "Snapshots:  snapper timeline on /" \
-    "Source:     nomarchy ${NOMARCHY_REV:0:12}${NOMARCHY_REV:+ }$([[ -z "${NOMARCHY_REV:-}" ]] && echo "(dirty tree) ")— pinned into the ISO, no network needed"
+    "Source:     nomarchy ${NOMARCHY_REV:0:12}${NOMARCHY_REV:+ }$([[ -z "${NOMARCHY_REV:-}" ]] && echo "(dirty tree) ")— $SOURCE_NET"
 
 if [[ "$UNATTENDED" != "1" ]]; then
     typed=$(gum input --placeholder "type the disk name ($(basename "$TARGET_DISK")) to confirm the wipe")