feat: add bitwise operations AND, OR, XOR, NOT, LSHIFT, RSHIFT

[tetsuo-cpp]

Summary

• Add six bitwise ops (AND, OR, XOR, NOT, LSHIFT, RSHIFT) to the Forth dialect for GPU kernel tiling and address alignment
• Binary ops reuse BinaryArithOpConversion; NOT uses a unary XOR-with-(-1) pattern
• RSHIFT uses arith::ShRUIOp (logical/unsigned shift)

Closes #3

Test plan

• Translation test: test/Translation/Forth/bitwise-ops.forth
• Conversion test: test/Conversion/ForthToMemRef/bitwise.mlir
• All 35 tests pass (cmake --build build --target check-warpforth)

[tetsuo-cpp]

Code Review

Overview

Adds 6 bitwise operations (AND, OR, XOR, NOT, LSHIFT, RSHIFT) across the full compiler stack: dialect definition, parser, MemRef conversion, and tests.

Correctness

• Binary ops (AND, OR, XOR, LSHIFT, RSHIFT): Correctly reuse BinaryArithOpConversion template — no new code to get wrong. arith op mappings are correct (AndIOp, OrIOp, XOrIOp, ShLIOp, ShRUIOp).
• NOT (unary): XOR with -1 (all bits set) is the correct bitwise complement for i64. Pattern correctly follows ZeroEqOpConversion structure — loads at SP, operates, stores back, SP unchanged.
• RSHIFT uses ShRUIOp (unsigned/logical): Correct per issue spec. Standard Forth RSHIFT is defined as logical shift.
• Parser: Words placed correctly after MOD, before @. Case-insensitive matching inherited from existing toUpperCase in the lexer.

Style & Conventions

• Op definitions follow the exact same boilerplate as existing arithmetic ops — consistent.
• Section header // Bitwise operations. with LLVM-style separators matches project convention.
• Stack effect comments in .td descriptions follow the ( input -- output ) pattern.
• clang-format already applied (formatting diff in patterns.add is cosmetic only).

Test Coverage

• Translation test covers all 6 words with full SSA chaining verification.
• Conversion test checks each op lowers to the correct arith.* op, including NOT's arith.constant -1 + arith.xori pattern.
• No pipeline (end-to-end) test, but this is consistent with how arithmetic and comparison ops were added — pipeline tests exercise combinations, not individual ops.

No Issues Found

Clean PR. The implementation is minimal and mechanical — 5 of 6 ops are one-line type aliases, the 6th (NotOpConversion) is a straightforward 10-line struct following an established pattern. No risks identified.