chore(deps): remove unused dependencies

[average-gary]

Summary

Remove 6 dependencies confirmed unused by two independent tools and manual source audit.

mujina-miner

• sha2 — the bitcoin crate provides SHA-256 via bitcoin_hashes; sha2 is never imported
• hyper (direct) — only used transitively via axum/reqwest, never imported directly
• modular-bitfield — never imported anywhere in source code

mujina-dissect

• hex — never imported
• thiserror — never imported
• tracing — never imported

Tool Evidence

cargo-machete (source-code heuristic, stable Rust)

Searches source files for use <crate> patterns. Finds zero matches for all 6 deps:

$ cargo machete
Analyzing dependencies of crates in this directory...
cargo-machete found the following unused dependencies in this directory:
mujina-dissect -- ./tools/mujina-dissect/Cargo.toml:
	hex
	thiserror
	tracing
mujina-miner -- ./mujina-miner/Cargo.toml:
	hyper
	modular-bitfield
	sha2

cargo +nightly udeps (compiler-level analysis)

Uses unstable compiler flags to determine which crates are actually linked:

$ cargo +nightly udeps --workspace
unused dependencies:
`mujina-miner v0.1.0`
└─── dependencies
     └─── "modular-bitfield"

cargo-udeps only flags modular-bitfield because sha2 and hyper are still compiled as transitive dependencies of other crates (axum, utoipa-swagger-ui). They are linked into the binary even though no source code imports them. Removing them as direct dependencies is still correct — they remain available transitively for the crates that actually need them.

Why both tools?

Tool	What it detects	Limitation
cargo-udeps	Deps not linked by the compiler at all	Misses deps that are linked transitively but never imported by your code
cargo-machete	Deps with no use or extern crate in source	Heuristic; can have false positives for crates used via macros or re-exports

Together they provide high confidence: modular-bitfield is confirmed by both tools. sha2, hyper, hex, thiserror, and tracing are confirmed by machete's source scan and corroborated by manual grep showing zero imports.

Impact

Eliminates 15 exclusive transitive dependencies from the build. Zero code changes — only Cargo.toml deletions.

Verification

• cargo check --workspace — pass
• cargo test --workspace --features skip-pty-tests — 283 passed, 0 failed
• cargo machete — clean (no unused deps detected after removal)
• cargo fmt --check — pass

Closes #34
See: #8

[average-gary]

Closing in favor of #32 which covers the same dependency removals and additionally fixes the pre-existing tracing.rs clippy warnings. Our audit in Discussion #8 corroborates the findings.