feat: click a coin row to view its trade history; edit transactions

Matches CoinMarketCap's flow: clicking anywhere on a coin's row in the
holdings table opens its transaction history (previously only a dedicated
icon button did). The table's own History icon is gone since the row now
does that job; the remaining "+"/delete icons get stopPropagation so they
don't also trigger the row click.

Adds the missing piece: transactions could be viewed and deleted but not
edited. New PATCH /crypto/transactions/{id} (partial update, never calls
CoinGecko, same oversell guard as creating a sell) backs a pencil button on
each history row that opens CryptoTransactionModal pre-filled — the same
dialog used for "+", now doing double duty as create/edit.

86/86 backend tests passing (4 new). Verified live against the real API:
create, edit quantity/note, 404 on unknown id, cleanup — real user data
untouched throughout.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01855PiW5Wd8n4aRW4n9kByY

frontend/src/lib/i18n.ts

@@ -128,6 +128,7 @@ const ru = {
   "crypto.form.noteLabel": "Заметка (необязательно)",
   "crypto.form.addTitle": "Добавить {{name}}",
   "crypto.form.tradeTitle": "Сделка: {{name}}",
+  "crypto.form.editTradeTitle": "Изменить сделку: {{name}}",
   "crypto.form.tradeButton": "Купить / продать",
   "crypto.form.buy": "Покупка",
   "crypto.form.sell": "Продажа",
@@ -589,6 +590,7 @@ const en: Record<keyof typeof ru, string> = {
   "crypto.form.noteLabel": "Note (optional)",
   "crypto.form.addTitle": "Add {{name}}",
   "crypto.form.tradeTitle": "Trade: {{name}}",
+  "crypto.form.editTradeTitle": "Edit trade: {{name}}",
   "crypto.form.tradeButton": "Buy / sell",
   "crypto.form.buy": "Buy",
   "crypto.form.sell": "Sell",