fix(formatter): Keep END_IF at same indent level as content

Per TIA Portal standard, END_IF stays at the same indent level as the
code inside the IF block, rather than decreasing. This matches the
reference file Em101Sequence.scl where nested END_IF statements are
properly aligned.

src/formatter.lua

@@ -285,7 +285,11 @@ function M.format_document(content, options)
           if_base_level = nil
         end
         in_fb_call = false  -- Reset FB call state
-        indent_level = math.max(0, indent_level - 1)
+        -- Don't decrease indent for END_IF - it stays at same level as content (per TIA Portal)
+        -- Only decrease for other enders like END_REGION, END_CASE, END_FOR, etc.
+        if kw ~= "END_IF" then
+          indent_level = math.max(0, indent_level - 1)
+        end
         if needs_semicolon(trimmed) then
           formatted_line = formatted_line .. ";"
         end