Pennant: all feature flags were replaced by BillingCycle, so remove the package
(composer), the now-empty app/Features discovery, the pennant-development skill,
and replace the create_features_table migration with a drop_features_table.
Timezone: the registration flow collected a user timezone (seeder, request
validation, hidden field) but no timezone column ever existed and CreateUser
discarded it. Remove the dead handling, the orphaned Timezone rule, and the
tests that covered the now-removed validation.
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