fix(graph): resolve instrument identity to stop wrong-company hallucination

Agents had no ground-truth ticker→company mapping, so the market analyst
could pattern-match a price chart to the wrong company (e.g. TOTDY read as
"TotalEnergies"), and every downstream agent inherited the bad framing.

Resolve identity once at run start via a cached, fail-open yfinance lookup
and inject company/sector/exchange into the shared instrument context that
all twelve agents consume, with an explicit do-not-substitute instruction.
Resolution runs on both the propagate() and CLI entry points.

Also replaces the bare "Continue" message-clear placeholder, which some
OpenAI-compatible providers interpreted as the user task, with a
context-anchored placeholder carrying the resolved identity and date.

#814 #888

tradingagents/graph/propagation.py

@@ -21,12 +21,21 @@ class Propagator:
         trade_date: str,
         asset_type: str = "stock",
         past_context: str = "",
+        instrument_context: str = "",
     ) -> Dict[str, Any]:
-        """Create the initial state for the agent graph."""
+        """Create the initial state for the agent graph.
+
+        ``instrument_context`` is the deterministic ticker-identity string
+        resolved once at run start (see
+        ``TradingAgentsGraph.resolve_instrument_context``). When empty, agents
+        fall back to ticker-only context via
+        ``get_instrument_context_from_state``.
+        """
         return {
             "messages": [("human", company_name)],
             "company_of_interest": company_name,
             "asset_type": asset_type,
+            "instrument_context": instrument_context,
             "trade_date": str(trade_date),
             "past_context": past_context,
             "investment_debate_state": InvestDebateState(