fix(rust): remediate clippy lint violations across all 14 Rust crates

Summary

PR #231 introduced clippy lint configuration ([lints.clippy] in all 14 Cargo.toml files) and CI enforcement (cargo clippy -- -D warnings) across both GitHub Actions and Azure DevOps pipelines. The CI gates are now active, but any existing clippy violations in the codebase will block PR merges. This issue tracks running clippy locally across all 14 crates and fixing any violations found.

Background

Current Lint Configuration (all 14 crates):

[lints.clippy]
correctness = { level = "deny", priority = -1 }
suspicious  = { level = "warn", priority = -1 }
complexity  = { level = "warn", priority = -1 }
style       = { level = "warn", priority = -1 }
perf        = { level = "warn", priority = -1 }

Three WASM crates (cdylib) additionally suppress missing_safety_doc = "allow".

CI Enforcement: cargo clippy -- -D warnings promotes all warn-level lints to errors. This means suspicious, complexity, style, and perf warnings all block builds.

Current Code State: No #[allow(clippy::...)] attributes exist anywhere in .rs source files, indicating either clean code or that violations have not yet been surfaced by CI.

Scope

14 Crates to Validate:

Acceptance Criteria

• cargo clippy -- -D warnings passes on all 11 standard crates
• cargo clippy --target wasm32-wasip2 -- -D warnings passes on all 3 WASM crates (cdylib)
• Fixes address root causes — prefer code corrections over #[allow(...)] suppressions
• Where #[allow(...)] is genuinely needed, include a justification comment
• CI pipelines pass on both GitHub Actions and Azure DevOps

Implementation Guidance

Run clippy across all crates locally:

for cargo_toml in $(find src/ -name "Cargo.toml" -not -path "./Cargo.toml"); do
  crate_dir=$(dirname "$cargo_toml")
  if grep -q 'crate-type.*=.*\["cdylib"\]' "$cargo_toml"; then
    (cd "$crate_dir" && cargo clippy --target wasm32-wasip2 -- -D warnings)
  else
    (cd "$crate_dir" && cargo clippy -- -D warnings)
  fi
done

Common clippy fixes by category:

• style: needless_return, redundant_closure, match_bool — simplify idioms
• complexity: too_many_arguments, type_complexity — extract helpers or type aliases
• perf: needless_collect, large_enum_variant — optimize allocations
• suspicious: suspicious_else_formatting, suspicious_op_assign_impl — clarify intent

Blocked by: #169 (clippy config + CI) — now merged via PR #231