List all Plaid bank connections (items) for the user.
Each item represents one institution (one bank login). A single
item can hold multiple Account rows (checking + savings + credit
card from the same bank).
Args:
include_inactive: Include unlinked / soft-deleted items (default: False)
Returns:
``{"items": [...], "total_count": N}`` where each item carries
id, institution_name, products (consented), last_synced_at,
is_active, error_code/message, consent_expiration_time, and
the count of currently-linked accounts.
ConnectorAPI key