fix(idle): skip DPMS-off when docked (#127 mitigation)

Blanking the only live output in dock mode led to a brick where wake and
even VT switch failed. Skip hypridle's 10m dpms off when any laptop
internal (eDP/LVDS/DSI) is present but not enabled; lock at 5m remains.
Undocked still blanks. Document LATER revisit for intentional
DPMS-when-docked once wake is proven.

V1: nix flake check --no-build. V3: docked idle stays lit under lock.

docs/ROADMAP.md

@@ -441,6 +441,12 @@ Design/decision records and a running log of shipped work (items marked
   `nomarchy-suspend` (hypridle + Power menu). LUKS: unlock session before
   encrypted hibernate phase so resume is LUKS-only (not hyprlock twice).
   Menu row self-gates on CanHibernate. V3: HARDWARE-QUEUE bag-carry test.
+- **Docked idle DPMS (#127 mitigation):** after a docked-idle brick (alive
+  machine, black external, undock no eDP, no usable Ctrl+Alt+F3), hypridle
+  **skips DPMS-off** when any laptop internal is present but not enabled
+  (dock/clamshell). Lock at 5 min unchanged; undocked still blanks at 10 min.
+  Intentional DPMS-when-docked is LATER (BACKLOG) once wake is proven.
+  Tooling kept: `nomarchy-display-wake` / `nomarchy-display-dump`.
 - ✓ **Generation prune (#128):** weekly `nomarchy-gen-prune` (system + HM):
   delete only gens older than **14 days** that are also beyond the **3 most
   recent past** gens (current always kept). Stock `nix.gc` no longer uses