Hide transfers in the transactions view by default

Transfers move money between your own accounts; at 433 of 3,996 rows
(~11%) they crowd out the rows that represent actual spending.

getTransactions gains `exclude_categories`, opt-in per caller and
deliberately not defaulted in queries.ts: the rules preview and the bulk
rule-apply path both read candidate rows through getTransactions, and a
default exclusion there would silently shrink what a rule can see and
reach — invisibly, since a rule that matches nothing looks the same as a
rule with nothing to do.

Two behaviours the filter needs, both tested:

- An explicit category pick beats the exclusion. Selecting "Transfers"
  while the default is on subtracts it from the hidden list instead of
  returning zero rows and reading as "you have no transfers".
- COALESCE the effective category to '' before `<> ALL`. NULL <> ALL(...)
  is NULL, not true, so an uncategorised row would disappear from a
  filter that never named its category — the trap EXCLUDE_NON_SPEND
  already documents.

The default is off when the view is scoped to a statement: that is a
reconciliation view, the row count has to match the statement, and a
credit-card payment is the row you went there to check.

src/__tests__/integration/queries.test.ts

@@ -105,6 +105,63 @@ describe("getTransactions — category filter", () => {
   });
 });
 
+describe("getTransactions — exclude_categories", () => {
+  it("hides the excluded category", async () => {
+    const { ownerId } = await seedParticipants(pool);
+    await insertTransaction(pool, ownerId, { description: "Grocery run", category: "groceries" });
+    await insertTransaction(pool, ownerId, { description: "Card payment", category: "transfers" });
+
+    const { data, total } = await getTransactions(ownerId, {
+      exclude_categories: ["transfers"], limit: 50, offset: 0,
+    });
+    expect(data).toHaveLength(1);
+    expect(total).toBe(1);
+    expect(data[0].description).toBe("Grocery run");
+  });
+
+  it("keeps uncategorised rows visible", async () => {
+    // NULL <> ALL(...) is NULL, not true. Without the COALESCE an uncategorised
+    // row would vanish from a filter that never named its category.
+    const { ownerId } = await seedParticipants(pool);
+    // insertTransaction defaults category to 'other', so insert directly.
+    await pool.query(
+      `INSERT INTO transactions (owner_id, statement_id, transaction_date, description, amount, transaction_type, category, row_index)
+       VALUES ($1, NULL, '2026-06-15', 'Unknown thing', 100, 'debit', NULL, 0)`,
+      [ownerId]
+    );
+
+    const { data } = await getTransactions(ownerId, {
+      exclude_categories: ["transfers"], limit: 50, offset: 0,
+    });
+    expect(data).toHaveLength(1);
+    expect(data[0].description).toBe("Unknown thing");
+  });
+
+  it("an explicit category pick beats the exclusion", async () => {
+    const { ownerId } = await seedParticipants(pool);
+    await insertTransaction(pool, ownerId, { description: "Card payment", category: "transfers" });
+
+    const { data } = await getTransactions(ownerId, {
+      categories: ["transfers"], exclude_categories: ["transfers"], limit: 50, offset: 0,
+    });
+    expect(data).toHaveLength(1);
+  });
+
+  it("respects the category override, not the raw category", async () => {
+    const { ownerId } = await seedParticipants(pool);
+    const txId = await insertTransaction(pool, ownerId, { description: "Was a transfer", category: "transfers" });
+    await pool.query(
+      `INSERT INTO transaction_overrides (transaction_id, category_override) VALUES ($1, 'investment')`,
+      [txId]
+    );
+
+    const { data } = await getTransactions(ownerId, {
+      exclude_categories: ["transfers"], limit: 50, offset: 0,
+    });
+    expect(data).toHaveLength(1);
+  });
+});
+
 describe("getTransactions — search filter", () => {
   it("searches description case-insensitively", async () => {
     const { ownerId } = await seedParticipants(pool);