apr eval --task: 8 of 10 dispatch arms are reachable but undocumented in --help #2584

apr eval --task dispatches 10 named arms plus the default perplexity path. --help
documents two.

Verified at HEAD (4bbfeb0)

Arms at crates/apr-cli/src/dispatch_analysis.rs:1383-1419:

classify  code  compare  contamination  correlation  human  humaneval  mbpp  plan  verify

Help at crates/apr-cli/src/extended_commands.rs:138:

/// Task type: omit for perplexity, "classify" for classification eval

Eight reachable and undocumented: humaneval, mbpp, code, contamination,
compare, verify, correlation, human, plan.

Why it matters

These are not dead arms — they dispatch. A user cannot discover apr eval --task humaneval from the tool, only from the source. For a benchmark command that is worse
than a missing feature: the capability exists, is unreachable by documentation, and its
absence from help implies it is unsupported.

Falsifier

A test that enumerates the dispatch arms at runtime and asserts every one appears in
the help text. The obvious weaker version — a hand-written list of expected arms — would
drift out of date exactly the way this did, and would have passed while eight arms were
undocumented.

Refs #2582