fix: prevent attribute block lines from being treated as assignments

The formatter was incorrectly treating multi-line attribute blocks as
assignments, causing AUTHOR/VERSION lines to get weird indentation.
Lines like:
  { S7_Optimized_Access := 'TRUE' }
  VERSION : 0.1

Were being processed incorrectly because the attribute block line
contains := but no semicolon, causing the formatter to treat the
next line as a continuation.

Fix by tracking in_attr_block state and skipping assignment detection
for lines inside or exiting attribute blocks.

src/formatter.lua

@@ -359,6 +359,7 @@ function M.format_document(content, options)
   local assignment_continuation_indent = ""
   local in_condition = false
   local condition_indent = ""
+  local in_attr_block = false
 
   for line_num, line in ipairs(lines) do
     local trimmed = line:gsub("^%s+", ""):gsub("%s+$", "")
@@ -377,6 +378,18 @@ function M.format_document(content, options)
 
     trimmed = collapse_attribute_block(trimmed)
 
+    -- Track if we're entering or exiting an attribute block
+    local has_open_brace = trimmed:find("{")
+    local has_close_brace = trimmed:find("}")
+    local exiting_attr_block = false
+    
+    if has_open_brace and not has_close_brace then
+      in_attr_block = true
+    elseif has_close_brace and not has_open_brace then
+      in_attr_block = false
+      exiting_attr_block = true
+    end
+
     -- Check if this line ends an assignment (has := and ends with ;)
     local ends_assignment = trimmed:match(":=") and trimmed:match(";%s*$")
 
@@ -602,7 +615,8 @@ function M.format_document(content, options)
     end
 
     -- Regular line - check for assignment start
-    if trimmed:match(":=") then
+    -- But not if its inside an attribute block, exiting one, or a single-line attribute block
+    if not in_attr_block and not exiting_attr_block and trimmed:match(":=") and not trimmed:match("^{.*}$") then
       local base_indent = get_indent()
       local assign_pos = trimmed:find(":=")
       if assign_pos then
@@ -620,6 +634,11 @@ function M.format_document(content, options)
       in_assignment = false
     end
     
+    -- Also reset assignment state when in attribute block
+    if in_attr_block then
+      in_assignment = false
+    end
+
     local formatted = get_indent() .. trimmed
     if NEEDS_SEMICOLON[kw] and trimmed:sub(-1) ~= ";" then
       formatted = formatted .. ";"