feat: multi-account Fio sync + switch QR default to 2502035405/2010

Add second Fio account (CZ0820100000002502035405 / 2502035405/2010).
Both accounts are fetched on every sync run and combined before dedup,
so the payments sheet accumulates transactions from either account.
QR codes now default to the new account.

Go:
- config.go: hardcoded Accounts/LoadedAccount slice replaces scalar
  BankAccount + FioAPIToken; Config.BankAccount renamed QRAccount;
  per-account tokens via FIO_API_TOKEN_NEW / FIO_API_TOKEN_OLD
- banksync.SyncToSheets: accepts []fio.Client, loops to combine txns
- cmd/fuj/main.go: buildFioClients helper; both sync call sites updated
- html_handler + build_adults/juniors: use Config.QRAccount
- New TestSyncToSheets_MultiAccount covers cross-account dedup

Python:
- config.py: ACCOUNTS list + LOADED_ACCOUNTS (tokens from env)
- fio_utils.py: fetch_transactions_for (per-account) +
  fetch_transactions_all (loops all accounts)
- sync_fio_to_sheets.py: uses fetch_transactions_all

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

scripts/fio_utils.py

@@ -103,7 +103,7 @@ def parse_czech_date(s: str) -> str | None:
 
 
 def fetch_transactions_transparent(
-    date_from: str, date_to: str, account_id: str = "2800359168"
+    date_from: str, date_to: str, account_id: str
 ) -> list[dict]:
     """Fetch transactions from Fio transparent account HTML page.
 
@@ -206,22 +206,47 @@ def fetch_transactions_api(
     return transactions
 
 
-def fetch_transactions(date_from: str, date_to: str) -> list[dict]:
-    """Fetch transactions, using API if token available, else transparent page."""
-    token = os.environ.get("FIO_API_TOKEN", "").strip()
+def fetch_transactions_for(account: dict, date_from: str, date_to: str) -> list[dict]:
+    """Fetch transactions for a single loaded account dict (from config.LOADED_ACCOUNTS).
+
+    Uses the API path if the account has a token, otherwise the transparent scraper.
+    date_from/date_to: YYYY-MM-DD.
+    """
+    token = (account.get("token") or "").strip()
+    acct_num = account["acct_num"]
     if token:
-        print(f"fio: using authenticated API, window {date_from}..{date_to}", file=sys.stderr)
+        print(f"fio: account {acct_num}: using authenticated API, window {date_from}..{date_to}", file=sys.stderr)
         return fetch_transactions_api(token, date_from, date_to)
 
     print(
-        f"fio: using transparent page (FIO_API_TOKEN unset — expect publishing lag), "
-        f"window {date_from}..{date_to}, account=2800359168",
+        f"fio: account {acct_num}: using transparent page (no token — expect publishing lag), "
+        f"window {date_from}..{date_to}",
         file=sys.stderr,
     )
-    # Convert YYYY-MM-DD to DD.MM.YYYY for the transparent page URL
     from_dt = datetime.strptime(date_from, "%Y-%m-%d")
     to_dt = datetime.strptime(date_to, "%Y-%m-%d")
     return fetch_transactions_transparent(
         from_dt.strftime("%d.%m.%Y"),
         to_dt.strftime("%d.%m.%Y"),
+        account_id=acct_num,
     )
+
+
+def fetch_transactions_all(
+    date_from: str, date_to: str, accounts: list[dict] | None = None
+) -> list[dict]:
+    """Fetch and combine transactions from all configured accounts.
+
+    accounts: list of loaded account dicts (defaults to config.LOADED_ACCOUNTS).
+    Returns a flat list of all transactions across all accounts.
+    """
+    if accounts is None:
+        from config import LOADED_ACCOUNTS
+        accounts = LOADED_ACCOUNTS
+    all_txns: list[dict] = []
+    for account in accounts:
+        txns = fetch_transactions_for(account, date_from, date_to)
+        print(f"fio: account {account['acct_num']}: {len(txns)} transaction(s)", file=sys.stderr)
+        all_txns.extend(txns)
+    print(f"fio: total {len(all_txns)} transaction(s) across {len(accounts)} account(s)", file=sys.stderr)
+    return all_txns