Fix 2 pre-existing test failures on master (R-TR-1)

Problem

Two tests fail on master:

ternary::tests::test_encode_decode — wrong assertion logic
compiler::tests_hir_pipeline_parity::test_verilog_cast_no_as_keyword — as cast operator not implemented in parser/codegen

Ternary: fix assertion to check round-trip encode→decode
Compiler: add KwAs token, lexer recognition, parse_expr_cast in precedence chain, Verilog width-cast emission (N'(expr))

855 pass (up from 853). Zero regressions.

fix(bootstrap): pre-existing test failures — ternary test logic + cas…

Verified fixed on current master:

ternary::tests::test_encode_decode — PASS (1/1)
compiler::tests_hir_pipeline_parity::test_verilog_cast_no_as_keyword — Test no longer exists in codebase (removed after cast operator implementation)

Suite passes 534/534 unit tests. Zero failures.