0.8.2 (part B): help command, did-you-mean, completions, man page, 100-column help, one error channel

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Part B of 0.8.2: the CLI's help, discovery and error surface brought to the standard of large-vendor CLIs, with the parser kept hand-rolled (no clap, MSRV 1.78, zero external crates). No new dependencies of any kind.

What changes

1. One command table (COMMANDS in probbit-cli/src/main.rs): every command, subcommand and flag with its arity, summary, usage, sections and examples. Every --help, probbit help, the completions and the man page render from it (usage.rs), and check_flags reads its flag lists from it, so help, completions and man cannot drift from what the parser accepts.
2. probbit help [COMMAND [SUBCOMMAND]]: identical text to COMMAND [SUBCOMMAND] --help; probbit help alone = probbit --help. persona and live subcommands now have their own help.
3. Did-you-mean: probbit: unknown command "persna"; did you mean "persona"? see \probbit --help` (Damerau-Levenshtein ≤ 2, ≤ 1 for words of ≤ 3 characters, or a unique prefix). Subcommands too (persona lnt→lint, live verfy→verify`). Exit code stays 2.
4. probbit completions bash|zsh|fish: static scripts from the table; unknown shell → exit 2 with the list.
5. 100-column help: top-level help starts with the version line, groups commands (persona · live · monitor · decide/run · mcp · other), ends with six examples; monitor --help split into usage / modes / flags / demo; the terminal hero screen fits 100 columns. Every flag and sentence of meaning kept.
6. One error channel (documented in docs/CHEATSHEET.md "Errors"): a human line on stderr always; a bad input's {"error"} object on stdout when stdout is not a terminal (unchanged for Python, MCP, npm, examples, scripts — all read it piped) or with --json; at a terminal without --json only the line, never both. Bad commands/flags stay off stdout unless --json (code: "flag", or "command" with "suggestion"), preserving Python's empty-stdout flag contract. --json is accepted by every command.
7. probbit man + committed docs/probbit.1 (test: equals the generated output). release.yml attaches probbit.1 (one line); install.sh installs it to ~/.local/share/man/man1/ (PROBBIT_MAN_DIR overrides), never fatally.
8. README Install, CHEATSHEET, CHANGELOG ## 0.8.2 - unreleased, CONTRIBUTING (regenerate docs/probbit.1 after a help change or version bump).

Before → after (0.8.1 → this branch)

	0.8.1	now
probbit help persona	unknown command, exit 2	persona help, exit 0
probbit persna init x.yaml	unknown command, no hint	did you mean "persona"?, exit 2
probbit completions zsh	unknown command	a zsh script (zsh -n clean)
probbit man	unknown command	roff page; man -l docs/probbit.1 renders
top-level help lines > 100 cols	10 of 15 (longest 447)	0
monitor --help	one 3,259-char paragraph block, longest line 205	sectioned, longest line ≤ 100
error at a terminal	line + JSON object	line only (--json for the object)

Tests

New: tests/cli_table.rs, cli_help.rs, cli_suggest.rs, cli_completions.rs, cli_layout.rs, cli_errors.rs (pipe, pseudo-terminal via script, --json), cli_man.rs; unit tests for the table and the distance. Existing help assertions updated for the new top-level layout. Locally: the full probbit-cli suite (release), the Python suite (44), npm/test-wrapper.cjs (13), examples/node/decide.mjs, scripts/bench/test_install_sh.sh and test_install_contract.py pass; cargo +1.78.0 build --release --locked --workspace is clean. zsh/fish syntax checks run where those shells exist (bash everywhere on Unix).

Notes

• Binary size: 2.33 MB → 2.46 MB (release, aarch64-apple-darwin), the help text and the generators.
• The man page header carries the version: the release bump must run cargo run -p probbit-cli -- man > docs/probbit.1 (the test names the command).
• At a terminal, probbit --help / probbit help still show the hero screen (as in 0.8.1, test hero_screen_at_a_terminal); the grouped list is what they print piped (probbit --help | less, which the hero now says).