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/hooks/useCrypto.ts

@@ -8,6 +8,7 @@ import {
   fetchCryptoHoldings,
   fetchCryptoTransactions,
   refreshCryptoPrices,
+  updateCryptoTransaction,
 } from "@/api/crypto";
 import type { CryptoHoldingCreateInput, CryptoRange, CryptoTransactionInput } from "@/types";
 
@@ -61,6 +62,15 @@ export function useAddCryptoTransaction() {
   });
 }
 
+export function useUpdateCryptoTransaction() {
+  const invalidate = useInvalidateCrypto();
+  return useMutation({
+    mutationFn: ({ transactionId, input }: { transactionId: number; input: CryptoTransactionInput }) =>
+      updateCryptoTransaction(transactionId, input),
+    onSuccess: invalidate,
+  });
+}
+
 export function useDeleteCryptoTransaction() {
   const invalidate = useInvalidateCrypto();
   return useMutation({