fix: align portfolio-hub ledger write adapter to live API contract

REQ-017 CHG-20260606-01. Live portfolio-hub returned 404 for the
trex-orbit-assumed POST /v1/assets/{asset_id}/ledger/trades. Correct to
POST /v1/portfolios/{portfolio_id}/ledger/trades with body keys
quantity/fee_amount/tax_amount (was qty/fee/tax), success 201. Reverified
with live e2e (201 Created, outbox COMPLETED) + durability drain of the
prior 404'd item. Resolves the REL-001 ledger-write release blocker.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

trex_core/adapters/ledger/portfolio_hub.py

@@ -1,12 +1,17 @@
 """portfolio-hub ledger HTTP adapter (REQ-017, dcy-004).
 
-Mirrors trex-orbit `PortfolioHubClient.post_ledger_trade`:
-  POST /v1/assets/{asset_id}/ledger/trades
-  body keys: side, qty, price, fee, tax, executed_at, execution_id, order_id
-  - 2xx              => recorded (or duplicate accepted idempotently)
+Live portfolio-hub contract (verified against openapi, REQ-017 CHG-04):
+  POST /v1/portfolios/{portfolio_id}/ledger/trades
+  body keys: side, quantity, price, fee_amount, tax_amount, executed_at,
+             execution_id, order_id
+  - 2xx (201)        => recorded (or duplicate accepted idempotently)
   - 409              => LedgerConflictError (operator resolution)
   - 4xx (other)/5xx  => LedgerRetryableError (outbox retries)
   - httpx error      => LedgerRetryableError
+
+`asset_id` on LedgerTrade carries the portfolio_id value (REQ-018:
+asset_id == portfolio_id), so it maps directly onto the {portfolio_id}
+path segment.
 """
 from __future__ import annotations
 
@@ -48,10 +53,10 @@ class PortfolioHubLedger:
     def _payload(trade: LedgerTrade) -> dict:
         return {
             "side": trade.side,
-            "qty": trade.qty,
+            "quantity": trade.qty,
             "price": trade.price,
-            "fee": trade.fee,
-            "tax": trade.tax,
+            "fee_amount": trade.fee,
+            "tax_amount": trade.tax,
             "executed_at": trade.executed_at.isoformat() if trade.executed_at else None,
             "execution_id": trade.execution_id,
             "order_id": trade.order_id,
@@ -65,7 +70,7 @@ class PortfolioHubLedger:
                           timeout=self._timeout)
 
     def record_trade(self, trade: LedgerTrade) -> LedgerWriteResult:
-        url = f"{self._base_url}/v1/assets/{trade.asset_id}/ledger/trades"
+        url = f"{self._base_url}/v1/portfolios/{trade.asset_id}/ledger/trades"
         try:
             resp = self._post(url, json=self._payload(trade))
         except httpx.HTTPError as exc: