csv-parser: keep LLM-mapped tickers; don't pass them through T212 mapping

The route's resolve-slice loop is T212-specific — it looks tickers up
against the InstrumentMap, which only has T212's universe. For the LLM
path the ticker is already Yahoo-ready (e.g. VOD.L, ASML.AS), so
sending it through resolve_slice produced spurious "could not be
resolved" warnings and dropped the positions.

Fix: ParsedPie gains a ``tickers_resolved`` flag (default False for
T212 backward-compat); _apply_mapping in the LLM path sets it True
and also extracts currency from the LLM-mapped currency_col into a
new ``ParsedPosition.currency`` field. The route branches on the flag:
LLM-path positions are kept verbatim with a best-effort InstrumentMap
lookup for nicer name/currency overrides, never dropped.

Integration test tightened to assert all 5 IBKR fixture positions
round-trip with the right currencies (USD / GBP / EUR).

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

app/routers/universe.py

@@ -225,19 +225,42 @@ async def parse_portfolio(
     unmapped: list[str] = []
 
     for p in pie.positions:
-        resolved = await resolve_slice(session, p.slice)
-        if resolved is None or not resolved.yahoo_ticker:
-            unmapped.append(p.slice or p.name or "?")
-            continue
+        if pie.tickers_resolved:
+            # LLM path: ``p.slice`` is already a Yahoo-ready ticker. We
+            # still do a best-effort InstrumentMap lookup so we can use
+            # the canonical name + currency when we happen to have one;
+            # but unlike the T212 path we never *drop* a position just
+            # because resolve_slice missed.
+            yahoo_ticker = p.slice.strip().upper()
+            if not yahoo_ticker:
+                unmapped.append(p.name or "?")
+                continue
+            resolved = await resolve_slice(session, yahoo_ticker)
+            name = (resolved.name if resolved else None) or p.name
+            currency = (
+                (resolved.currency if resolved else None)
+                or p.currency or "USD"
+            )
+        else:
+            # T212 path: ``p.slice`` is a shortcode that MUST round-trip
+            # through the InstrumentMap. Drop unmapped positions — the
+            # warnings block surfaces them to the user.
+            resolved = await resolve_slice(session, p.slice)
+            if resolved is None or not resolved.yahoo_ticker:
+                unmapped.append(p.slice or p.name or "?")
+                continue
+            yahoo_ticker = resolved.yahoo_ticker
+            name = resolved.name or p.name
+            currency = resolved.currency
         positions_out.append({
-            "yahoo_ticker": resolved.yahoo_ticker,
+            "yahoo_ticker": yahoo_ticker,
             "t212_slice": p.slice,
-            "name": resolved.name or p.name,
+            "name": name,
             "qty": p.quantity,
             "avg_cost": p.average_price,    # @property — no call parens
-            "currency": resolved.currency,
+            "currency": currency,
         })
-        yahoo_tickers.append(resolved.yahoo_ticker)
+        yahoo_tickers.append(yahoo_ticker)
 
     # Synchronous upsert: bypass the Redis buffer so the dashboard has
     # live prices immediately. The buffer + flush machinery remains for