Add EUR/USD support with modular per-pair signal producer pattern

- Register EUR/USD in config (pip 0.0001, EurUsdStrategyConfig)
- Create pair_signals/ module: registry + dispatcher with per-pair
  config factories (xauusd.py, eurusd.py) for easy add/remove
- EUR/USD gets forex-tuned regime weights, London+NY session hours,
  XAU strategy gates disabled
- Add defense-in-depth display_name guards in signal_aggregator
- Rename telegram_bot.py → testing_telegram_bot.py with separate
  bot token, both pairs with dedicated button rows
- Add EUR/USD to news engine affected pairs map
- 9 new tests (146 total, all passing)
- Zero changes to engine.py, data_provider.py, main.py, backtest/

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pair_signals/__init__.py

@@ -0,0 +1,52 @@
+"""
+Per-pair signal producers.
+
+Each pair module exposes:
+    make_config(primary_tf, confirmation_tfs) -> PlatformConfig
+
+To add a new pair: create pair_signals/<pair>.py with make_config(),
+then register it in this file.
+"""
+
+from typing import Optional, List, Dict, Callable
+
+from config import PlatformConfig, Timeframe
+from signal_aggregator import SignalAggregator, SignalReport
+from data_provider import ForexDataProvider
+
+PAIR_PRODUCERS: Dict[str, Callable] = {}
+
+
+def register_pair(symbol: str, config_factory: Callable):
+    PAIR_PRODUCERS[symbol] = config_factory
+
+
+def get_supported_pairs() -> List[str]:
+    return list(PAIR_PRODUCERS.keys())
+
+
+def produce_signal(
+    symbol: str,
+    primary_tf: Timeframe,
+    data_provider: ForexDataProvider,
+    confirmation_tfs: Optional[List[Timeframe]] = None,
+) -> SignalReport:
+    config_factory = PAIR_PRODUCERS.get(symbol)
+    if config_factory is None:
+        raise ValueError(
+            f"No signal producer registered for {symbol}. "
+            f"Available: {list(PAIR_PRODUCERS.keys())}"
+        )
+
+    config = config_factory(primary_tf, confirmation_tfs)
+    aggregator = SignalAggregator(config)
+    aggregator.data_provider = data_provider
+    return aggregator.analyze_pair(symbol=symbol)
+
+
+from pair_signals import xauusd as _xau_mod
+from pair_signals import eurusd as _eur_mod
+from config import XAUUSD, EURUSD
+
+register_pair(XAUUSD, _xau_mod.make_config)
+register_pair(EURUSD, _eur_mod.make_config)