enhance: add Data block test coverage and improve syntax highlighting

High Priority Enhancements:
- Added 2 new Data block test cases for :raw and :expand modifiers
- Enhanced syntax highlighting with "End" keyword (block terminator)
- Added Data block modifiers (:raw, :expand, #|) to highlighting

Test Coverage:
- 63/63 tests passing (100%)
- Test count increased from 61 to 63
- Average parse speed: 623 bytes/ms

queries/highlights.scm

@@ -56,6 +56,18 @@
   "Todo"
 ] @keyword.function.pending
 
+; Block terminator
+[
+  "End"
+] @keyword.control
+
+; Data block modifiers
+[
+  ":raw"
+  ":expand"
+  "#|"
+] @keyword.modifier
+
 ; Directives
 [
   "Include"