fix: hoist local M = {} above closures to resolve M.get_theme

_dispatch_event captures M at closure-definition time; with M declared
further down the file, the capture resolved to global M (nil), causing
'attempt to index a nil value (global M)' every frame the panel was open
and a mouse event was dispatched. Hoisting the table declaration above
the dispatch helpers fixes the resolution at compile time.

init.lua

@@ -34,6 +34,11 @@
 -- Module-level state (all local — no globals)
 -- -----------------------------------------------------------------------
 
+-- Module-table declared early so closures in module-local helpers below
+-- can reference M.X functions. Method assignments (function M.x() ... end)
+-- still land further down once the public surface section starts.
+local M = {}
+
 local widgets             = {}      -- widget_id (string) → widget_def table
 local active              = nil     -- active widget_id or nil
 local theme               = {}      -- merged DEFAULT_THEME + overrides
@@ -187,11 +192,8 @@ local function _dispatch_event(event)
 end
 
 -- -----------------------------------------------------------------------
--- Public module table
+-- Public API (M declared at top of file so closures above can reference it)
 -- -----------------------------------------------------------------------
-
-local M = {}
-
 -- -----------------------------------------------------------------------
 -- Registry / Lifecycle
 -- -----------------------------------------------------------------------