Add @vitest/coverage-v8 and configure coverage in vitest.config.ts
to report on src/**/*.ts (excluding types.ts). Adds text and html
reporters, a test:coverage script, and gitignores the coverage dir.

Cover previously untested subcommands and branches:
- members: list pagination/--all/--order/empty, create with all options,
  update --email/no-options, export, import (success/skip/failure/fields),
  find (field/plan/combined), stats, bulk-update (run/dry-run/missing-id/email),
  bulk-add-plan (no-plan/dry-run/unknown-filter)
- records: query, export (default/custom path), import (success/skip/failure/
  data-prefix), bulk-update (run/dry-run/missing-id), bulk-delete
  (run/dry-run/no-matches)

Cover the CLI entry point behaviors:
- Banner prints to stderr by default
- Banner suppressed with --quiet and -q flags
- NO_COLOR set from --no-color argv or NO_COLOR env
- All 13 commands registered via addCommand
- parseAsync called, default action shows help

Cover all branches of the login flow including successful OAuth,
authorization errors, missing code/state, state mismatch, non-callback
404 paths, registration failure, and error without description.

…rices, and tables

Cover error handlers, optional fields, and branch conditions across all
five command modules to improve statement coverage from 70-80% to 95-100%.

Test program name, description, version, usage, registered options,
configureHelp reordering, and preAction hook for --live/--sandbox flags.

Add new test files to project tree listing, document test:coverage
command, and note @vitest/coverage-v8 in dev dependencies.