Unify notion db command descriptors to prevent parser/help drift

The notion db cleanup removed the remaining public migrate/repair leaves and aligned docs/tests, but the command surface is still described in multiple places: the import-safe Effect CLI descriptor, the handwritten Node parser/help text, and the Nix wrapper dispatch list.\n\nFollow-up: define a single internal command descriptor or add a focused drift test that proves parser-accepted commands, help/completions, and Nix dispatch stay aligned.\n\nThis is not blocking the current clean-break CLI surface, but it would reduce future redundancy and accidental public-surface drift.

Start by locating the import-safe Effect CLI descriptor, the handwritten Node parser/help text, and the Nix wrapper dispatch list. Compare their accepted commands, help/completions, and dispatch behavior; done means a shared descriptor or focused drift test keeps these surfaces aligned.