feat(overlay): forward mpv mouse and wheel bindings through overlay

- Accept WHEEL_UP/DOWN/LEFT/RIGHT (with modifiers) in keybindings, the plugin, and the settings key editor
- Forward mpv's MBTN_* and WHEEL_* bindings from the overlay so double-click fullscreen, wheel volume, and similar inputs work on Hyprland; SubMiner bindings and right-click pause still win
- Notify the overlay via mpv-input-bindings:changed when mpv's key set changes, fixing dead imported keys when the overlay loads before mpv connects
- Sync README requirements/quick start with the installation guide and fix the Arch MeCab install command (AUR mecab-git)

scripts/test-plugin-session-bindings.lua

@@ -291,6 +291,14 @@ local ctx = {
 						actionType = "mpv-command",
 						command = { "sub-seek", -1 },
 					},
+					{
+						key = {
+							code = "WHEEL_UP",
+							modifiers = { "ctrl" },
+						},
+						actionType = "mpv-command",
+						command = { "add", "sub-scale", 0.1 },
+					},
 					{
 						key = {
 							code = "KeyW",
@@ -386,6 +394,7 @@ local expected_mpv_bindings = {
 	{ keys = "q", command = { "quit" } },
 	{ keys = "Ctrl+w", command = { "quit" } },
 	{ keys = "MBTN_BACK", command = { "sub-seek", -1 } },
+	{ keys = "Ctrl+WHEEL_UP", command = { "add", "sub-scale", 0.1 } },
 }
 
 for _, expected in ipairs(expected_mpv_bindings) do