fix(trips): money that came back is not what the trip cost

Every trip figure filtered on transaction_type IN ('debit','fee','interest'),
which drops refunds and credits outright. A partly-refunded booking therefore
read at its full price and the refund subtracted nothing, anywhere: the
headline total_spend, the category breakdown, the daily chart, top merchants
and the tag breakdown were all gross.

This is the same defect the general analytics fixed once already, which is why
NET_SPEND_ROWS and SPEND_SIGNED exist -- a refunded Expedia purchase read as
$2,888.92 of spend until they did. Trip analytics never adopted them. Doing so
now costs one predicate and one expression per query.

getTrips/getTripById needed the trips alias moved to `tr`: the fragments assume
`t` is `transactions`, and hand-inlining a copy rather than renaming is exactly
how the reconciled-row exclusion drifted out of the analytics routes before.

On Europe 2026 this is $821.12 -- a LuxuryEscapes booking with two part-credits
against it, and a FreeNow hold adjustment. Fully cancelled bookings are a
different case and are handled by untagging both legs from the trip by hand,
because a trip never incurred a cost it cancelled.

No balance moves: the owed query already excludes credits and a refund carries
no split. There is a test asserting exactly that, and it passes with or without
this change -- it is a guard, not a proof. The three that do prove it fail
without it.

src/__tests__/integration/queries.test.ts

@@ -8,7 +8,7 @@ mockDbWithPool(pool);
 
 // Dynamic import AFTER the mock ensures getTransactions / getParticipantBalances
 // use the test pool rather than Prisma's singleton.
-const { getTransactions, getParticipantBalances, getTripAnalytics } = await import("@/lib/queries");
+const { getTransactions, getParticipantBalances, getTripAnalytics, getTripById } = await import("@/lib/queries");
 
 beforeEach(async () => {
   await resetDB(pool);
@@ -466,3 +466,75 @@ describe("getTripAnalytics — owner scoping", () => {
     expect(Number(carol!.owed)).toBeCloseTo(150);
   });
 });
+
+// A refunded trip expense must not still read as trip cost. These queries
+// filtered on debit/fee/interest, so a refund was dropped entirely and the
+// original purchase stood at full value.
+describe("getTripAnalytics — refunds reduce trip cost", () => {
+  async function seedTripWithRefund(ownerId: number) {
+    const trip = await pool.query(
+      `INSERT INTO trips (owner_id, name, start_date, end_date)
+       VALUES ($1, 'Refund Trip', '2026-03-01', '2026-03-10') RETURNING id`,
+      [ownerId]
+    );
+    const tripId = trip.rows[0].id as number;
+
+    const spend = await insertTransaction(pool, ownerId, {
+      amount: 200, category: "travel", description: "Hotel booking", transaction_date: "2026-03-02",
+    });
+    const refund = await insertTransaction(pool, ownerId, {
+      amount: 50, category: "travel", description: "Hotel partial refund",
+      transaction_type: "refund", transaction_date: "2026-03-05",
+    });
+    await pool.query(
+      `INSERT INTO transaction_overrides (transaction_id, trip_id) VALUES ($1, $3), ($2, $3)`,
+      [spend, refund, tripId]
+    );
+    return tripId;
+  }
+
+  it("nets the refund out of the category total", async () => {
+    const { ownerId } = await seedParticipants(pool);
+    const tripId = await seedTripWithRefund(ownerId);
+
+    const { category_breakdown } = await getTripAnalytics(tripId, ownerId);
+    const travel = category_breakdown.find((c) => c.category === "travel");
+    expect(Number(travel!.amount)).toBeCloseTo(150);
+  });
+
+  it("nets the refund out of the trip's headline total_spend", async () => {
+    const { ownerId } = await seedParticipants(pool);
+    const tripId = await seedTripWithRefund(ownerId);
+
+    const trip = await getTripById(tripId, ownerId);
+    expect(Number(trip!.total_spend)).toBeCloseTo(150);
+  });
+
+  it("shows the refund as a negative on its own day", async () => {
+    const { ownerId } = await seedParticipants(pool);
+    const tripId = await seedTripWithRefund(ownerId);
+
+    const { daily_spend } = await getTripAnalytics(tripId, ownerId);
+    const refundDay = daily_spend.find((d) => d.date === "2026-03-05");
+    expect(Number(refundDay!.amount)).toBeCloseTo(-50);
+  });
+
+  // The owed side must be untouched: a refund carries no split, and the owed
+  // query deliberately excludes credits. Netting cost must not move a balance.
+  it("leaves what the other participant owes unchanged", async () => {
+    const { ownerId, otherId } = await seedParticipants(pool);
+    const tripId = await seedTripWithRefund(ownerId);
+    const rows = await pool.query(
+      `SELECT transaction_id FROM transaction_overrides WHERE trip_id = $1 ORDER BY transaction_id`,
+      [tripId]
+    );
+    await pool.query(
+      `INSERT INTO transaction_splits (transaction_id, participant_id, share_percent) VALUES ($1, $2, 50)`,
+      [rows.rows[0].transaction_id, otherId]
+    );
+
+    const { participant_splits } = await getTripAnalytics(tripId, ownerId);
+    const bob = participant_splits.find((r) => r.participant_id === otherId);
+    expect(Number(bob!.owed)).toBeCloseTo(100);
+  });
+});