feat(hints): #73 fingerprint + doctor MOTD/first-boot tips

#43 shipped Firmware MOTD + control-center --first-boot tip. Residual:
- MOTD always lists nomarchy-doctor; Fingerprint line only when
  nomarchy.hardware.fingerprint.enable (no nag without a reader).
- first-boot tips self-gate on fprintd-list / nomarchy-doctor (same
  gum style as Firmware). No dismiss state file — first-boot is once.

V0 flake check --no-build + bash -n; V1 build control-center + eval
MOTD with/without fingerprint.enable. V3 enroll stays hardware-queue.

pkgs/nomarchy-control-center/nomarchy-control-center.sh

@@ -39,10 +39,21 @@ function first_boot() {
         fi
     fi
     
+    # Post-install hardware/day-2 tips (#43 Firmware; #73 fingerprint +
+    # doctor). Self-gated on the same CLI presence the System menu uses;
+    # first-boot is once, so no dismiss state file is needed.
     if command -v fwupdmgr >/dev/null 2>&1; then
         gum style --foreground 245 \
             "Tip: SUPER+M → System › Firmware checks LVFS updates (never auto-flashes)."
     fi
+    if command -v fprintd-list >/dev/null 2>&1; then
+        gum style --foreground 245 \
+            "Tip: SUPER+M → System › Fingerprint to enroll a finger (or fprintd-enroll)."
+    fi
+    if command -v nomarchy-doctor >/dev/null 2>&1; then
+        gum style --foreground 245 \
+            "Tip: run nomarchy-doctor (or SUPER+M → System › Doctor) for a read-only health check."
+    fi
 
     gum style --foreground 212 "First boot configuration complete!"
     echo "You can always change these later in the Control Center."