feat: add testing framework with reference project integration

- Add test/ directory with test harness and test files
- Add UDT, DB, FB parser tests
- Add PLC JSON and integration tests
- Test against reference project (239 UDTs, 12 DBs, 37 SCL, 13 XML)
- Fix attribute parsing to handle underscores (S7_SetPoint)
- Add ORGANIZATION_BLOCK support to FB parser

lua/scl/fb_parser.lua

@@ -62,10 +62,10 @@ local function parse_attributes(attr_str)
 
   local attrs = {}
   -- Match key := 'value' or key := value patterns
-  for key, value in attr_str:gmatch("(%w+)%s*:=%s*'([^']+)'") do
+  for key, value in attr_str:gmatch("([%w_]+)%s*:=%s*'([^']+)'") do
     attrs[key] = value
   end
-  for key, value in attr_str:gmatch("(%w+)%s*:=%s*(%w+)") do
+  for key, value in attr_str:gmatch("([%w_]+)%s*:=%s*(%w+)") do
     attrs[key] = value
   end
   return attrs
@@ -166,7 +166,7 @@ local function parse_var_section(content, section_name)
   return vars
 end
 
--- Parse FB/Function content
+-- Parse FB/Function/OB content
 function M.parse_fb_content(content, filename)
   local fb = {
     filename = filename,
@@ -189,11 +189,17 @@ function M.parse_fb_content(content, filename)
       fb_type = "FUNCTION"
       -- Extract return type if present
       fb.return_type = content:match('FUNCTION%s+"[^"]+"%s*:%s*(%w+)')
+    else
+      -- Try ORGANIZATION_BLOCK
+      fb_name = content:match('ORGANIZATION_BLOCK%s+"([^"]+)"')
+      if fb_name then
+        fb_type = "ORGANIZATION_BLOCK"
+      end
     end
   end
 
   if not fb_name then
-    return nil, "No FUNCTION_BLOCK or FUNCTION definition found"
+    return nil, "No FUNCTION_BLOCK, FUNCTION, or ORGANIZATION_BLOCK definition found"
   end
 
   fb.name = fb_name