Setup only — do NOT build crypto yet, that is the next task.

This part continues the product you already built — the ledger,
receipts, and money held in several currencies.

Same repository, same documented commands. If you are starting in an
empty folder, your earlier work is fetched for you before you begin.

Before writing anything new, check that what you carried in still stands:

• AGENTS.md still declares stack:, run: and test:;
• the suite the test: line names is green;
• the parts already delivered are still delivered.

And check the product itself, not only its suite. These must still be true
of what you carried in:

• the March book still balances at 3223.70, and receipts still become
  drafts a person confirms
• a 120.00 USD entry on 2026-03-14 still keeps its 120.00 USD and
  reports as 112.80 EUR
• a date without a rate is still shown as missing rather than guessed

Fix whatever the hand-over broke before you start this part — a judge reads
the product on this rung, and everything the earlier parts earned is judged
again at the end of it, so a regression carried in quietly costs twice.

Coins sit next to cash now: bought in fractions, priced by a market that
moves while nobody is looking, and worth being honest about. You decide when
it is done; a judge panel scores the result.

The prices the product knows, in the home currency EUR:

Scenarios:

Scenario: Buying a fraction
When 0.01750000 BTC is bought on 2026-03-02
Then the holding reads 0.01750000 BTC
And it cost 1071.70 EUR, which the product remembers

Scenario: Eight decimals survive
When 0.00000001 BTC is added to a holding
Then the holding says so, to the last decimal
And no amount is ever rounded on its way in or out

Scenario: What it is worth today
Given the holding of 0.01750000 BTC bought on 2026-03-02
When it is valued on 2026-03-20
Then it is worth 1030.75 EUR
And the unrealised result reads -40.95

Scenario: Selling settles part of it
When 0.00750000 BTC is sold on 2026-03-20
Then 0.01000000 BTC is left
And the realised result of -17.55 is recorded

Scenario: Cash and coins in one number
Then the money the person has is one figure in the home currency
And it includes accounts and holdings alike

Scenario: A price that is missing
When today's price of an asset is unknown
Then the holding is shown at the last price the product knows, with its date
And never as zero

Everything beyond the scenarios is yours: where prices come from, how a
wallet is added, how gains are presented.

When you are done, write .ololo/money-tracker-crypto-done.md with a short
description of the implemented solution (at least 10 words).