Rust performance and maintainability wins

[timopruesse]

Summary

14 commits — one per item — applying the Apollo Rust best practices to tighten performance hot paths and reduce duplicated code. Each commit is self-contained and passes cargo test + cargo clippy -- -D warnings.

Performance (P1–P8)

• P1 — stop cloning the full AppConfig when constructing TaskRunner; move it in after the requires_sudo check
• P2 — std::mem::take instead of cloning selected task names in select_tasks
• P3 — iterate filtered_indices directly in the TUI task-list render (removes one HashSet<usize> alloc per frame at ~20 Hz)
• P4 — for bash/zsh, pipe the in-memory script straight to stdin instead of writing-then-reading a temp file. PowerShell (which needs -File) is the only remaining temp-file path
• P5 — RunArgs::all_command_strings now returns impl Iterator<Item = &str>; no Vec<&str> alloc on every description render or requires_sudo scan
• P6 — HashSet lookup for selected task names in requires_sudo
• P7 — topological_sort returns Cow<'a, [String]>; the no-deps fast path borrows instead of cloning every name
• P8 — tighter to_string_lossy usage: into_owned instead of .to_string(), and reuse the resolved PathBuf in setup.rs so canonicalize doesn't re-parse a string

Maintainability (M1–M6)

• M1 — config::resolve_config_dir helper replaces three copies of the canonicalize-parent-or-fallback idiom
• M2 — utils::process::stream_and_wait replaces the duplicated child-stdout/stderr plumbing in run.rs and clone.rs; parameterized on whether stderr should carry the [stderr] tag (shell) or pass through (git progress)
• M3 — utils::path::walk_relative replaces the WalkDir + strip_prefix + ignore loop duplicated across copy.rs and symlink.rs (install + uninstall)
• M4 — Display impls on each args struct as single source of truth; CommandEntry::Display and each executor's description() now delegate. Side effect: list command output now shows the (sudo) marker, which is more informative
• M5 — rewrote validate_env_key with let-else so the empty-string check and .next().unwrap() collapse into one branch
• M6 — create_executor takes CommandEntry by value; ownership transfer is explicit at the single caller (iter().cloned()) and the match arms move args into the executor without an internal clone

One trailing style: apply rustfmt commit covers line-length reflows from the new helpers.

Test plan

• cargo test — all 31 tests pass
• cargo clippy --all-targets --all-features -- -D warnings — clean
• cargo fmt --check — clean
• Manual smoke test of install / update / uninstall on a real config
• Verify TUI still renders correctly and is responsive during heavy output
• Verify git clone output is readable without [stderr] noise

🤖 Generated with Claude Code