Refresh fund NAVs from AMFI, and report how old prices are

[iamabhi9]

Three problems, all from the same root: prices were only ever updated by a broker sync,
and nothing told you how old they were.

1. Fund NAVs now refresh from AMFI

python3 app/navs.py            # fetch and mark every fund
python3 app/navs.py --dry-run  # show what would change, write nothing

AMFI publishes every Indian scheme's NAV daily as one public text file — no key, no
account, nothing personal sent.

This matters most for Paytm, which reports no NAV at all. Those funds were marked at
the NAV of their last transaction; the oldest was 24 days stale. Refreshing moved the
India total by about 0.1%.

Matching refuses to guess. A NAV on the wrong fund is worse than a stale one — a stale
price is visibly stale, a wrong one is not.

• ISIN where the holding has one (Zerodha).
• Paytm has none, so the scheme name must reduce to exactly one Direct/Growth scheme
  after filler words are dropped. Correctly matched HDFC Index Fund - BSE Sensex Plan →
  AMFI's HDFC BSE Sensex Index Fund despite the word order.
• Regular plans and IDCW options excluded — an IDCW NAV would permanently understate a
  growth holding.
• Anything ambiguous is skipped and reported, never resolved.
• Resolved ISINs are stored, so a name is matched once and can be audited.

2. "Data through" measured the wrong thing

It reported the last transaction date. A trade this morning made the header look healthy
while fund NAVs were a month old. Price age is now reported per asset class as the
oldest mark in each group — one fund priced today does not make the fund holdings
current — shown beside the transaction date and bannered past a week.

3. The quotes table was dead

Written by upsert_quotes, read by nothing, 0 rows. It now backs pricing. A quote is used
only when dated later than the broker snapshot, so a stale quote can never override a
fresh sync.

A bug the tests found

results() had a second pricing path for holdings with no transactions — which is
every mutual fund — that read positions.price directly and ignored quotes entirely. The
funds this feature exists to reprice were the one group it would not have reached. Both
paths now go through _positions().

Evidence

$ python3 run_tests.py
PASSED — 102 unit tests, plus the XIRR solver suite

$ python3 scripts/check_clean.py
clean — 73 files safe to commit; 1 account number(s) checked for

	before	after
India value	stale marks	current NAVs
Worst price age	24d	1d
quotes rows	0	8

realized + unrealized + dividends == net_profit holds in both markets.

Not covered: equities. AMFI is funds only; stock prices still come from the broker at
sync time.