Fix: consensus endpoint matched on username, which is usually empty

[mpont91]

/api/consensus/markets selects smart traders by username, then filters trades with it:

WITH smart_traders AS (
    SELECT username FROM polybot.aware_smart_money_scores FINAL
    WHERE total_score >= 45 LIMIT 100
)
...
WHERE username IN (SELECT username FROM smart_traders)

Most Polymarket wallets have no username set, so both sides are the empty string for the majority of rows. The subquery matches almost nothing real, and the endpoint returns signal_count: 0 even when smart money is clearly clustered in the same markets.

proxy_address is always populated and is the key the rest of the scoring pipeline already uses.

Verified

Same database, same thresholds, before and after:

before:  {"signal_count": 0, "signals": []}
after:   20 signals — e.g. 5 traders on "Bitcoin Up or Down - Aug 25",
                           3 traders on "Will Southampton FC win on 2026-08-25?"