Oanda demo daemon: auto-execution on practice account (XAU/USD)

New independent trading daemon (oanda_daemon.py) that places orders on
an Oanda v20 practice account instead of sending Telegram alerts.
Oanda-only market data (oanda_provider.py, mid candles + real bid/ask
spread) through the unchanged signal pipeline; order execution and
trade management via oanda_executor.py (raw requests, no new deps).

Book parity with the backtester: no broker-side TP (exits = SL/TRAIL/
TIMEOUT only), bar-close-only trail ratchet with each closed bar
processed exactly once, 5-bar per-TF entry cooldown, structural SL
from the setup. Accepted divergence: one position total (skipped
signals logged for book reconciliation).

Safety/ops: fail-fast boot on rejected credentials (transient outages
continue), market orders never retried (double-fill risk), entry lock
against aligned-boundary races, restart recovery + adoption via
oanda_state.json, hourly heartbeat, asyncio exception handler, every
failure path logged. Prices formatted at instrument precision.

Config: env OANDA_* -> config.json "oanda" section (validated in
app_config). Tests: Module 15 (30 tests), suite 240 green.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VUnCqjWBuvKRSjLwHeB9BJ

config.json.example

@@ -20,5 +20,13 @@
       "blocked_hours_utc": [0, 1, 2, 10, 11, 13, 16, 21]
     }
   },
+  "oanda": {
+    "account_id": "REPLACE_WITH_ACCOUNT_ID",
+    "api_token": "REPLACE_WITH_API_TOKEN",
+    "base_url": "https://api-fxpractice.oanda.com",
+    "lot_size": 1,
+    "quality_gate": "C",
+    "max_hold_bars": 300
+  },
   "log_level": "INFO"
 }