feat(cash): mark how a transaction was paid, exclude cash from reconciliation

getPendingReconciliations treated every unreconciled manual transaction as
awaiting a matching statement row. Cash never appears on a statement, so a cash
entry sat in the queue indefinitely being offered matches within 3 days and 1%
on amount - and accepting one is silently destructive: reconciled manual rows
are filtered out of every query, so the cash spend disappears while the card
transaction it matched claims to be that same spend.

Migration 0016 adds transactions.payment_method (card | cash | bank_transfer |
other, NULL = unknown) with a CHECK constraint and a partial index. The notCash()
fragment excludes cash from both halves of the reconciliation query - the pending
list and the candidate match subquery, which aliases the manual row as m.

Only cash is excluded. Bank transfers do appear on a statement now that
transaction accounts are imported, and NULL means unknown, so both stay
candidates and every pre-existing row behaves exactly as before.

ATM withdrawals deliberately stay categorised as spend rather than transfers.
Treating them as transfers is only correct if every cash purchase is logged;
with partial logging it silently deletes the unlogged remainder from spend.

src/lib/hooks.ts

@@ -104,6 +104,7 @@ export function useCreateTransaction() {
       transaction_type?: string;
       merchant_normalized?: string;
       category?: string;
+      payment_method?: string;
       splits?: { participant_id: number; share_percent: number }[];
     }) => {
       const res = await fetch("/api/transactions", {
@@ -140,6 +141,7 @@ export function useUpdateTransaction() {
       amount?: number;
       transaction_date?: string;
       trip_id?: number | null;
+      payment_method?: string | null;
     }) => {
       const res = await fetch(`/api/transactions/${id}`, {
         method: "PATCH",