Add niri-animations plugin (#223)

Animation preset picker for niri: choose a .kdl preset, set the global
slowdown factor, or turn animations off. Ships a floating and a
bar-attached panel plus a control-center tile.

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

niri-animations/shortcut.luau

@@ -0,0 +1,36 @@
+--!nonstrict
+-- Control-center tile: opens the picker panel, and lights up while animations are enabled.
+--
+--   shortcut.setLabel(text)
+--   shortcut.setIcon(on [, off])
+--   shortcut.setActive(bool)
+--   shortcut.setEnabled(bool)
+
+-- target_file is declared as a root-level [[setting]], which seeds every entry. Shortcuts do
+-- NOT receive entry-level ([[panel.setting]]) values, so keeping the fallback here is what
+-- makes this file survive someone moving that setting back under an entry.
+local TARGET = noctalia.getConfig("target_file") or "~/.config/niri/animations.kdl"
+
+local function animationsOn(): boolean
+  local text = noctalia.readFile(TARGET)
+  if text == nil then return true end
+  return string.match(text, "\n%s*off%s*[\n\r]") == nil
+end
+
+local function render()
+  local on = animationsOn()
+  shortcut.setLabel(noctalia.tr("shortcut_label"))
+  shortcut.setIcon("movie")
+  shortcut.setActive(on)
+  shortcut.setEnabled(true)
+end
+
+render()
+
+-- The tile opens the ATTACHED variant: it is pressed from the control center, which already
+-- sits against the bar, so a panel floating in the middle of the screen would feel detached.
+-- Bind the `picker` entry to a key for the floating one.
+function onClick()
+  noctalia.runAsync("noctalia msg panel-toggle imjustdoingmypart/niri-animations:docked")
+  render()
+end