ppvm-pauli-word-2 Patch (#246)

This patch introduces the ppvm-pauli-word-2 crate from
#204. On top of the crate
shown in that PR, this patch also includes the following:
- Separate parsing and formatting, phase representation, hashing, and
gate operations into into modules
- Reject construction beyond backing-storage capacity, including
identity-only strings.
- Reject mixed-width multiplication and column insertion/replacement.
- Enforce logical qubit bounds in column toggles, Clifford gates, and
symplectic mutations.
- Reject identical qubits in two-qubit Clifford gates before mutation.
- Removed Clone for PauliStorage

Author: JonhasA

Cargo.lock

@@ -23,6 +23,7 @@ members = [
     "crates/ppvm-vihaco",
     "crates/ppvm-cli",
     "crates/ppvm-traits-2",
+    "crates/ppvm-pauli-word-2",
     # Runnable copies of the Rust code blocks in skills/ppvm-usage/SKILL.md.
     # Built by `cargo build --workspace --all-targets` in CI so the skill
     # can't silently drift away from the public API.

Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "ppvm-pauli-word-2"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+ppvm-traits-2 = { version = "0.1.0", path = "../ppvm-traits-2"}
+bitvec = "1.0.1"
+bytemuck = { version = "1", features = ["min_const_generics"] }
+fxhash = "0.2.1"
+num = "0.4.3"