feat(session): first-boot welcome toast (#81)

One-shot user unit fires a dismissible "You're set" notification on the
first graphical session (SUPER+M / SUPER+T / SUPER+? + Network + Doctor),
then writes settings.firstBootShown into the flake checkout. Skips the
live ISO hostname (hosts/live.nix keeps its own toast). Toggle:
nomarchy.firstBootWelcome.enable. checks.first-boot covers the gate.

Verified: V2 — flake check --no-build; checks.first-boot green; local
shim smoke; downstream-template-home ships the unit.

agent/JOURNAL.md

@@ -19,6 +19,21 @@ Template:
 
 ---
 
+## 2026-07-11 — #81 first-boot welcome toast
+- **Task:** NEXT #81 — dismissible “you're set” card (`VISION § B`).
+- **Did:** `pkgs/nomarchy-first-boot` + user oneshot
+  (`modules/home/first-boot.nix`): notify once with SUPER+M/T/? + Network
+  + Doctor pointers; marker `settings.firstBootShown` via theme-sync
+  `--no-switch` (in-checkout state). Skip live hostname. Option
+  `nomarchy.firstBootWelcome.enable` (default on). `checks.first-boot`.
+  ROADMAP/VISION/README; closed #81.
+- **Verified:** **V2** — `nix flake check --no-build`; `checks.first-boot`
+  green (toast + marker + silent re-run + live skip); local shim smoke;
+  downstream-template-home carries the user unit.
+- **Pending:** V3 — real swaync rendering on first installed login
+  (toast body is pure text; not queued unless it misbehaves).
+- **Next suggestion:** #82 generation readability or #85 docs hall of fame.
+
 ## 2026-07-11 — #80 doctor battery health readout
 - **Task:** NEXT #80 — battery health in `nomarchy-doctor` (`VISION § C`).
 - **Did:** Doctor row: `cycle_count` + retained capacity