feat(keyboard): interactive new-keyboard layout prompt + persist

The runtime-remember complement to nomarchy.keyboard.devices. Set
nomarchy.keyboard.layouts (candidate layouts) and a nomarchy-keyboard-watch
daemon runs (exec-once): it polls hyprctl devices, and when a keyboard
connects after login that isn't declared and hasn't been chosen before, it
pops a rofi layout picker, applies the choice via hyprctl switchxkblayout (an
index into the candidate set carried by input.kb_layout), and remembers it
per-device in ~/.local/state -- re-applied silently on later reconnects. The
boot-time set (incl. the built-in keyboard) is never prompted.

Pure bash + jq/hyprctl/rofi (all in the session PATH); state lives outside
the flake (a stateful runtime piece by design). Eval + bash-syntax verified;
the hotplug behaviour needs an on-hardware test.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/ROADMAP.md

@@ -293,17 +293,20 @@ how to override it. Items marked ✓ are shipped.
     declarative way). A Waybar `hyprland/language` indicator shows the active
     layout, gated on more than one layout being in play (comma in the session
     layout, or any per-device override) so single-layout bars stay clean.
-  - **Interactive new-keyboard prompt (runtime + persist):** a small daemon
-    listening to Hyprland's socket for keyboard hotplug — when an *unknown*
-    keyboard connects, pop a rofi layout picker, apply the choice
-    (`hyprctl switchxkblayout` among a configured candidate set, or reload the
-    device config), and persist it per-device to a state file so it re-applies
-    automatically on every later reconnect. The runtime-remember complement to
-    the declarative `nomarchy.keyboard.devices` above (set it once, on the fly,
-    no config editing). Nice bridge: offer to also write the choice into
-    `nomarchy.keyboard.devices` so it graduates into the reproducible config.
-    Note: a stateful runtime piece (like the wallpaper) — it sits outside the
-    pure-declarative model by design.
+  - ✓ **Interactive new-keyboard prompt (runtime + persist):** set
+    `nomarchy.keyboard.layouts` (candidate layouts) and a `nomarchy-keyboard-
+    watch` daemon runs (exec-once): it polls `hyprctl devices`, and when a
+    keyboard connects *after* login that isn't in `keyboard.devices` and
+    hasn't been chosen before, it pops a rofi layout picker, applies the
+    choice with `hyprctl switchxkblayout` (an index into the candidate set,
+    which `input.kb_layout` carries), and remembers it per-device in
+    `~/.local/state/nomarchy/keyboard-layouts` — re-applied silently on later
+    reconnects. The boot-time set (incl. the built-in keyboard) is never
+    prompted. The runtime-remember complement to the declarative
+    `keyboard.devices`; a stateful runtime piece by design. **Pending an
+    on-hardware test** (hotplug isn't verifiable in CI). Remaining (bonus):
+    offer to write a choice into `keyboard.devices` so it graduates to the
+    reproducible config.
   - Remaining: a multi-layout cycle bind (`hyprctl switchxkblayout` / xkb
     `grp:` options) for switching layouts on one keyboard; add the
     `hyprland/language` module to the summer whole-swap themes for parity