feat: implement for-loops with proper scope management

- Add support for C-style for loops: for (init; condition; increment) { body }
- Implement three-level scoping: loop context + per-iteration contexts
- Add semicolon disabler for increment statements using RAII guards
- Support break/continue/return control flow with scope validation
- Fix semicolon handling in parser for flexible for-loop syntax

include/Ast/astBase.hpp

@@ -47,6 +47,7 @@ namespace Fig::Ast
 
         VarAssignSt,
         WhileSt,
+        ForSt,
         ReturnSt,
         BreakSt,
         ContinueSt,