feat(statements+analytics): normalise statement_type; fix analytics scoping

Groundwork for importing bank and loan statements alongside credit cards.

statement_type was whatever free text Gemini put in account_type ('Credit Card',
'credit card', 'credit_card', 'Business Card', 'ACCESS ADVANTAGE',
'multi-currency account'). The UI coped only by doing .includes("card"), which
breaks as soon as bank and loan statements arrive.

- Migration 0013 adds normalize_statement_type() + a BEFORE INSERT/UPDATE
  trigger and a CHECK constraint over credit_card|transaction|savings|loan|
  offset|investment|other. The trigger means the N8N workflow keeps working
  unchanged while it still sends free text. Raw value stays in account_type.
  Backfilled 99 existing rows.
- src/lib/statement-types.ts mirrors the vocabulary for the UI; statements page
  now filters by the real types and headlines balance vs amount due per type.

Analytics were scoped with INNER JOIN statements + s.owner_id, which silently
dropped all 180 manual/CSV transactions (statement_id IS NULL) from every
report. Switched all six routes to LEFT JOIN + COALESCE(t.owner_id, s.owner_id)
via shared fragments in src/lib/analytics-sql.ts, so the transfers/investment
exclusion that stops card-payment double counting stays consistent. Also
extended that exclusion to trip analytics, which had none.

Drive-by: /api/analytics/subscriptions was returning 500 on an unserialisable
BigInt from COUNT(*) + 1.

Verified against the live DB: monthly spend picks up the previously invisible
manual transactions (Apr 9,849.91 -> 14,286.70) and all four analytics
endpoints return 200.

src/app/statements/page.tsx

@@ -3,6 +3,12 @@
 import { useState, useMemo } from "react";
 import Link from "next/link";
 import { useStatements, useParticipants, useUpdateStatement } from "@/lib/hooks";
+import {
+  STATEMENT_TYPES,
+  STATEMENT_TYPE_LABELS,
+  asStatementType,
+  isLiability,
+} from "@/lib/statement-types";
 
 function formatDate(d: string | null) {
   if (!d) return "—";
@@ -40,7 +46,7 @@ export default function StatementsPage() {
   const updateStatement = useUpdateStatement();
 
   const [bankFilter, setBankFilter] = useState("");
-  const [typeFilter, setTypeFilter] = useState<"all" | "card" | "bank">("all");
+  const [typeFilter, setTypeFilter] = useState<"all" | (typeof STATEMENT_TYPES)[number]>("all");
   const [ownerFilter, setOwnerFilter] = useState("");
   const [yearFilter, setYearFilter] = useState("");
 
@@ -63,10 +69,8 @@ export default function StatementsPage() {
   const filtered = useMemo(() => {
     if (!statements) return [];
     return statements.filter((s) => {
-      const isCard = s.statement_type?.toLowerCase().includes("card") ?? false;
       if (bankFilter && s.bank_name !== bankFilter) return false;
-      if (typeFilter === "card" && !isCard) return false;
-      if (typeFilter === "bank" && isCard) return false;
+      if (typeFilter !== "all" && asStatementType(s.statement_type) !== typeFilter) return false;
       if (ownerFilter && String(s.owner_id) !== ownerFilter) return false;
       if (yearFilter && s.billing_end_date?.slice(0, 4) !== yearFilter) return false;
       return true;
@@ -98,8 +102,9 @@ export default function StatementsPage() {
 
           <select value={typeFilter} onChange={(e) => setTypeFilter(e.target.value as typeof typeFilter)} className={selectCls}>
             <option value="all">All types</option>
-            <option value="card">Credit card</option>
-            <option value="bank">Bank account</option>
+            {STATEMENT_TYPES.map((t) => (
+              <option key={t} value={t}>{STATEMENT_TYPE_LABELS[t]}</option>
+            ))}
           </select>
 
           {participants && participants.length > 1 && (
@@ -152,10 +157,14 @@ export default function StatementsPage() {
             </thead>
             <tbody>
               {filtered.map((s, idx) => {
-                const isCreditCard = s.statement_type?.toLowerCase().includes("card") ?? false;
-                const displayAmount = isCreditCard ? s.total_amount_due : s.closing_balance;
+                const stmtType = asStatementType(s.statement_type);
+                const owed = isLiability(s.statement_type);
+                // Cards headline the amount due; everything else (including loans,
+                // where the balance is what's still owed) headlines the balance.
+                const displayAmount =
+                  stmtType === "credit_card" ? s.total_amount_due : s.closing_balance;
                 const amount = Number(displayAmount);
-                const amountColor = isCreditCard
+                const amountColor = owed
                   ? "text-red-400"
                   : amount >= 0
                   ? "text-green-400"
@@ -185,7 +194,7 @@ export default function StatementsPage() {
                       {formatPeriod(s.billing_start_date, s.billing_end_date)}
                     </td>
                     <td className="px-4 py-3 text-zinc-400 whitespace-nowrap">
-                      {isCreditCard ? formatDate(s.payment_due_date) : formatDate(s.billing_end_date)}
+                      {formatDate(s.payment_due_date ?? s.billing_end_date)}
                     </td>
                     <td className="px-4 py-3 text-zinc-500 text-xs">
                       {s.currency}