feat: add keybind cheatsheet plugin (#64)

* feat: add keybind cheatsheet

* docs: refresh keybind cheatsheet preview

* docs: use official generated keybind thumbnail

* feat(keybind-cheatsheet): preload cached snapshots

Move parser and cache ownership into an event-driven data service so the panel opens from a prepared last-known-good snapshot. Document the plugin's inspiration and independent v5 implementation.

keybind-cheatsheet/widget.luau

@@ -0,0 +1,26 @@
+--!nonstrict
+-- Static, event-only bar entry. Parsing and cache ownership belong to the data
+-- service; this widget only toggles the panel or requests a refresh.
+
+local PANEL_ID = "kenn/keybind-cheatsheet:cheatsheet"
+local REFRESH_REQUEST_KEY = "keybind-cheatsheet.refresh-request"
+
+local function render()
+  barWidget.setGlyph(noctalia.getConfig("glyph") or "keyboard")
+  barWidget.setTooltip(noctalia.tr("widget_tooltip"))
+end
+
+function onClick()
+  noctalia.togglePanel(PANEL_ID)
+end
+
+function onIpc(event, _payload)
+  if event == "toggle" then
+    noctalia.togglePanel(PANEL_ID)
+  elseif event == "refresh" then
+    local generation = tonumber(noctalia.state.get(REFRESH_REQUEST_KEY)) or 0
+    noctalia.state.set(REFRESH_REQUEST_KEY, generation + 1)
+  end
+end
+
+render()