fix(traffic): prevent phantom quota consumption from stale node data (#5412)

Three related bugs caused inflated traffic counters and spurious quota
hits on multi-node setups, most visibly when a client email was renamed
while a node was offline or its PostgreSQL deadlocked.

**Fix 1 — phantom quota (root cause)** `setRemoteTrafficLocked`
new-row path: when master had no `client_traffics` row for an email
that a node reported, it seeded the row with `Up: cs.Up` — importing
the node's full accumulated counter as if it were fresh quota usage.
If the node retained stale data from a previously-deleted account (e.g.
a failed deletion during an outage), the ghost 50 GB appeared on the
new client immediately and triggered `disableInvalidClients` the same
tick. Fixed by seeding at `Up: 0`; the current node value still becomes
the baseline so only future increments count.

**Fix 2 — PostgreSQL deadlock** `addClientTraffic` did a
read-modify-write via `tx.Save(slice)`, issuing UPDATEs in slice order.
Two concurrent goroutines locking the same rows in opposite order
deadlock on PostgreSQL (SQLite avoids this with file-level
serialisation). Replaced with atomic per-email
`UPDATE SET up=up+?, down=down+?` statements. Also preserves the
delayed-start ExpiryTime conversion that `adjustTraffics` computes
in-memory but the old Save path persisted to the DB.

**Fix 3 & 4 — stale `inbound_id` filters** `autoRenewClients` used
`WHERE inbound_id NOT IN (node inbounds)` to skip node clients, but
`client_traffics.inbound_id` is set once on INSERT and never refreshed.
Replaced with an email-based subquery through `client_inbounds` (the
authoritative source). Also added a safe type assertion for
`settings["clients"].([]any)` that previously panicked on nil.

**Fix 5 — stale `inbound_id` in reset** `resetAllClientTrafficsLocked`
used `WHERE inbound_id = ?` to find which emails to reset; same staleness
problem. Replaced with the `client_inbounds` join for email lookup;
the `inbounds.last_traffic_reset_time` update still correctly uses the
inbound ID directly on the `inbounds` table.

Tests updated to reflect the new seeding-at-zero semantics and a new
`TestGhostData_NoPhantomTraffic` test reproduces the exact 50 GB
phantom scenario.

internal/web/service/inbound_node.go

@@ -559,8 +559,8 @@ func (s *InboundService) setRemoteTrafficLocked(nodeID int, snap *runtime.Traffi
 					Total:      cs.Total,
 					ExpiryTime: cs.ExpiryTime,
 					Reset:      cs.Reset,
-					Up:         canon.Up,
-					Down:       canon.Down,
+					Up:         0,
+					Down:       0,
 					LastOnline: cs.LastOnline,
 				}
 				if err := tx.Clauses(clause.OnConflict{Columns: []clause.Column{{Name: "email"}}, DoNothing: true}).