refactor(price): enhance currency handling with FX conversion and cache support

- Add `get_fx_rate()` function with caching to fetch foreign exchange rates from open.er-api.com
- Introduce `get_currency()` helper to map market codes to currency identifiers
- Update price parsing regex to support multiple currency symbols (£, $, €)
- Convert shares to float to accommodate fractional holdings
- Add currency, fx_rate, and total_value_gbp fields to output JSON
- Support fractional share counts (e.g., 3.6185 AAPL shares)

holdings.sample.csv

@@ -1,3 +1,4 @@
 GGP,GB,100
 PAF,GB,200
 SVM,US,50
+AAPL,US,3.6185

price.py

@@ -5,31 +5,63 @@ import sys
 import requests
 from bs4 import BeautifulSoup
 
+FX_CACHE = {}
+
+def get_fx_rate(currency):
+    if currency in FX_CACHE:
+        return FX_CACHE[currency]
+    if currency == "GBP":
+        return 1.0
+    url = f"https://open.er-api.com/v6/latest/{currency}"
+    r = requests.get(url, timeout=20)
+    rate = r.json()["rates"]["GBP"]
+    FX_CACHE[currency] = rate
+    return rate
+
 def get_price(market, ticker):
     url = f"https://web.freetrade.io/universe/{market}/{ticker}"
     response = requests.get(url, headers={
         "User-Agent": "Mozilla/5.0"
     }, timeout=20)
     text = BeautifulSoup(response.text, "html.parser").get_text(" ", strip=True)
-    m = re.search(r"Latest price\s*:\s*[£$]([0-9,.]+)", text)
+    m = re.search(r"Latest price\s*:\s*[£$€]([0-9,.]+)", text)
     if m:
         return float(m.group(1).replace(",", ""))
     return None
 
+def get_currency(market):
+    return {"GB": "GBP", "US": "USD"}.get(market, "GBP")
+
 holdings_file = sys.argv[1] if len(sys.argv) > 1 else "holdings.csv"
 
 results = []
 with open(holdings_file) as f:
     reader = csv.reader(f)
     for row in reader:
-        ticker, market, shares = row[0].strip(), row[1].strip(), int(row[2].strip())
+        ticker, market, shares = row[0].strip(), row[1].strip(), float(row[2].strip())
+        currency = get_currency(market)
         price = get_price(market, ticker)
+        if price is None:
             results.append({
                 "ticker": ticker,
                 "market": market,
+                "currency": currency,
+                "shares": shares,
+                "price": None,
+                "fx_rate": None,
+                "total_value_gbp": None
+            })
+            continue
+        fx = get_fx_rate(currency)
+        total_gbp = round(price * shares * fx, 2)
+        results.append({
+            "ticker": ticker,
+            "market": market,
+            "currency": currency,
             "shares": shares,
             "price": price,
-            "total_value": round(price * shares, 2) if price is not None else None
+            "fx_rate": fx,
+            "total_value_gbp": total_gbp
         })
 
 print(json.dumps(results, indent=2))