Issue #3605874: Add `ddev storybook` management command and keep Storybook working across DDEV restarts

See #3605874.

Adds a single ddev storybook command (alias ddev sb) with subcommands init | enable | disable | list | status | stats | doctor | gen | build | help, a post-start hook that re-applies the Storybook dev-services (CORS) include wiped by DDEV's settings.ddev.php regeneration, and a fix for the storybook:ddev yarn script (export $(cat ...) is not parseable by yarn's shell).

• init delegates to ddev init-storybook (kept).
• enable/disable toggle dev services; disable is sticky across restarts.
• doctor diagnoses common scenarios and prints the exact fix command.