Implement integer bitwise operators

[itsfuad]

Goal

Add finite-width integer bitwise operators through normal compiler pipeline.

Scope

• Unary complement: ~.
• Binary AND, OR, XOR: &, |, ^.
• Checked shifts: <<, >>.
• Integral-only typing with normal common numeric conversion.
• Arithmetic right shift for signed integers; logical right shift for unsigned integers and byte.
• Compile-time rejection and runtime trap for shift counts outside [0, bit_width).
• Conventional precedence from shifts through logical operators.
• Positive runtime and negative semantic fixtures.

Explicit Non-Scope

• Compound bitwise assignments.
• Bitwise operations on bool, floats, rawptr, or composites.
• SIMD/vector operators.

Validation

• Focused lexer, parser, typechecker, constvalue, consteval, HIR/MIR, LLVM, and pipeline tests.
• Positive and negative x_test fixtures.
• Capped full Go suite, vet, bundle, diff, format, and artifact checks.