Multi-node sync/import drift can leave the same client twice inside an
inbound's legacy settings.clients JSON while the normalized
client_inbounds table stays clean (SyncInbound dedupes the rows it
writes but never rewrites the JSON). All three subscription builders
iterated that JSON verbatim, so every duplicate entry became a
duplicate profile in the raw, Clash, and JSON output.
Filter and dedupe by email in one shared helper (link generation keys
purely on inbound + email, so same-email entries are pure duplicates
and dropping them is lossless). The clash/json services' own
inboundService copies became unused and are removed.