fix(formatter): correctly indent variables in VAR_IN_OUT sections

The get_keyword() function was using pattern ^(%w+_%w+) which only
matched up to the second underscore, causing VAR_IN_OUT to be
extracted as VAR_IN. Since VAR_IN is not in VAR_KEYWORDS, the
VAR_IN_OUT block was not being pushed onto the stack.

Fixed by changing the pattern to ^([%w_]+) to capture the entire
keyword including all underscores.

This ensures variables inside VAR_IN_OUT, VAR_CONSTANT, and other
multi-underscore VAR sections are properly indented.

src/formatter.lua

@@ -260,7 +260,8 @@ function M.format_document(content, options)
 
   -- Helper: extract keyword from line
   local function get_keyword(trimmed)
-    return trimmed:match("^(%w+_%w+)") or trimmed:match("^(%w+)")
+    -- Match VAR_IN_OUT, VAR_CONSTANT, etc. (words with multiple underscores)
+    return trimmed:match("^([%w_]+)") or trimmed:match("^(%w+)")
   end
 
   -- Helper: find case block in stack
@@ -498,7 +499,7 @@ function M.format_document(content, options)
       goto continue
     end
 
-    -- Regular line
+    -- Regular line (including variable declarations inside VAR sections)
     local formatted = get_indent() .. trimmed
     -- Add semicolon if it looks like it needs one
     if NEEDS_SEMICOLON[kw] and trimmed:sub(-1) ~= ";" then