feat(power): clamshell — ignore lid suspend when docked (#86)

Explicit HandleLidSwitchDocked=ignore under services.logind so closing
the lid with an external display connected does not suspend. Undocked
lid path left to upstream defaults. checks.clamshell-logind asserts the
baked logind.conf and active logind; real multi-monitor lid V3 queued.

Verified: V2 — flake check --no-build; checks.clamshell-logind green.
V3 pending: HARDWARE-QUEUE #86 lid+external on a laptop.

agent/HARDWARE-QUEUE.md

@@ -11,6 +11,14 @@ the **T14s** (webcam case).
 
 ## Any machine (dev box is fine)
 
+- [ ] **#86 clamshell lid + external display** — V2 asserts
+      `HandleLidSwitchDocked=ignore` in logind.conf. On a laptop with a
+      real external monitor: open a session, plug external, close lid —
+      machine must **stay awake** (no suspend); external panel remains
+      usable (or wakes with keyboard if DPMS). Unplug external, close lid
+      — should suspend as usual. Optional: with a docked display-profile
+      (`eDP-1` disable), confirm clamshell layout still looks right after
+      lid close. Pass = no surprise suspend when docked.
 - [ ] **#55 fingerprint enroll on real reader** — with
       `nomarchy.hardware.fingerprint.enable` and a physical reader: System ›
       Fingerprint › Enroll a finger; List shows it; Verify succeeds; optional