capture execution block split in architecture docs

Author: mgomes

docs/architecture.md

@@ -22,8 +22,9 @@ Key files:
 - `vibes/execution_expressions.go` (expression dispatch and evaluation)
 - `vibes/execution_assign.go` (assignment targets and member assignment flow)
 - `vibes/execution_script.go` (script call surface and function argument binding)
-- `vibes/execution_calls.go` (callable dispatch + function invocation + block invocation)
+- `vibes/execution_calls.go` (callable dispatch + function invocation)
 - `vibes/execution_call_expr.go` (call expression target/args/kwargs/block evaluation)
+- `vibes/execution_blocks.go` (block literal creation and block/yield invocation)
 - `vibes/execution_operators.go` (unary/index/binary operator evaluation)
 - `vibes/execution_control.go` (range/case/loop/try evaluation)
 - `vibes/execution_errors.go` (runtime error model, wrapping, and quota/signal sentinels)