#371 fix: suggest search alexandria for alexandria search, and list subcommands after unknown-command errors

Two CLI-only errors that the API can't help with, because they're about CLI command shapes:

• firecrawl alexandria search <query> was sent to Find Tools as categories: ["search"]. It now fails without making a request: unknown command 'search'. Did you mean firecrawl search alexandria '<query>'?. The message respects --json, --pretty and --output, and the query is shell-quoted.
• Every command group now lists its subcommands after commander's unknown-command error. For example, firecrawl research search adds Commands of firecrawl research: search-papers, inspect-paper, related-papers, read-paper. Before, "Did you mean" appeared only for near-spellings.

Other unknown categories (firecrawl alexandria 3d) show the API's message unchanged. Since firecrawl/exchange#1207, that message names the rejected ID, lists the valid categories and points to query.