refactor: remove AI-generated slop across modules

[weboko]

What

A module-by-module sweep of this Rust CLI to remove AI-generated slop. All edits are minimal and behavior-preserving, except one real bug fix (setup.rs). Verified with cargo check (clean, no warnings) and cargo test --no-run (all targets compile).

Bug fix

• src/commands/setup.rs — sha256_hex never computed SHA-256. sha2 is a plain, non-optional dependency and the crate has no [features] table, so #[cfg(feature = "sha2")] was always false and the FNV-1a fallback was what compiled. The function returned a 16-char non-SHA digest, so prebuilt sequencer_service verification (setup.rs:348) compared it against a published 64-char .sha256 and always mismatched → bail!, silently breaking the --prebuilt path whenever a checksum file existed. Now uses sha2 unconditionally, matching the project's existing hex-encode idiom (run_state.rs::hex_encode).

Slop cleanup (no behavior change)

• src/config.rs — removed a dead let path = format!("modules.{name}"); binding that was only consumed by let _ = path; (plus its "Defensive:" comment).
• src/commands/basecamp.rs — removed #[allow(dead_code)] // Fields wired up in later phases on BasecampAction (all variants are constructed; compiles clean without it); collapsed a verbose two-arm cwd_override match into as_deref().unwrap_or(project_root), matching the idiom the file's own tests already use.
• src/commands/run.rs — stripped redundant // Step N: comment prefixes that just duplicate the user-facing [N/total_steps] progress prints; all explanatory text preserved.
• src/commands/wallet_support.rs — collapsed a stray run of spaces in the legacy wallet-config warning string.

Notes on what was not changed

The codebase is otherwise well-maintained. Several flagged "redundant" defensive checks (e.g. .exists() after a non-empty-path guard in basecamp.rs) were verified to be legitimate — a non-empty path string doesn't guarantee the binary is on disk — and were intentionally left as-is. Idiomatic nested if let optional-chaining (no let-chains on rustc 1.81) and the well-documented non-cryptographic fnv1a_64 helper were also left untouched.

https://claude.ai/code/session_01KutAyMX3auZUKhuHHp5xXq

[Copilot]

Pull request overview

This PR performs a small refactor pass to remove unused/low-signal code and comments across several modules, and fixes a latent checksum bug in the --prebuilt download path by making sha256_hex compute a real SHA-256 digest unconditionally.

Changes:

• Fix sha256_hex to always use sha2 and return a proper 64-char SHA-256 hex digest for prebuilt integrity verification.
• Remove an unused/discarded local binding during TOML serialization (serialize_config), reducing dead code.
• Clean up user-facing text and inline pipeline comments without changing behavior.

Reviewed changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated no comments.

File	Description
src/commands/setup.rs	Makes prebuilt checksum verification correct by computing SHA-256 via sha2 unconditionally.
src/config.rs	Removes an unused path binding and discard statement in serialize_config.
src/commands/run.rs	Simplifies pipeline step comments (keeps user-facing progress output unchanged).
src/commands/wallet_support.rs	Normalizes spacing in a legacy wallet-config warning message.

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[weboko]

closing in favor of #210