fix(cli): sort top-level help with clap display order

[MintsInc]

Context

pup#269 established that top-level commands in pup --help should be alphabetically sorted. Enum declaration order was a valid proxy while every command was hand-written, but #[command(flatten)] keeps generated commands contiguous and prevents them from being interleaved with hand-written variants.

This caused pup#829 to render generated commands such as downtimes at the end of help instead of between downtime and error-tracking.

Using separate hand-written and generated blocks was considered, but clap provides only one top-level command heading, so the result would look incorrectly sorted and become more pronounced as generation expands. Assigning a shared display order lets clap sort the complete command list by name. Display order affects help placement only; command parsing is unchanged.

Clap checks duplicate command names and aliases only in debug builds. Because a duplicate top-level name or alias can behave ambiguously in release builds, this PR adds an explicit uniqueness regression test across generated and hand-written commands.

Changes

• Add a shared clap command constructor that assigns the same display order to every top-level subcommand.
• Use the constructor for runtime parsing, agent-help schema construction, and the command tree passed to static shell completion generators.
• Document that display-order normalization applies only to top-level commands.
• Retarget the existing alphabetical-order regression test at rendered help instead of enum insertion order.
• Parse only command rows within the rendered Commands: section, excluding wrapped descriptions and later help sections.
• Add regression coverage for uniform display order, alphabetical interleaving, and unique top-level command names and aliases, including hidden aliases.

Tests

• cargo build
• cargo fmt --check
• cargo clippy --all-targets -- -D warnings
• cargo test -- --test-threads=1 — 2,018 passed
• Verified pup --help remains alphabetically sorted.
• Verified pup --agent --help still emits the agent schema.
• Verified Bash and Zsh completion generation succeeds.
• Browser WASM build was not run locally because the wasm32-unknown-unknown target and rustup are unavailable; CI covers this configuration.