Add Alpaca equities ingest adapter

Adds an Alpaca-backed equities adapter with exchange metadata mapping for conservative off-exchange tagging and a small helper test suite.

services/ingest-equities/tests/alpaca.test.ts

@@ -0,0 +1,29 @@
+import { describe, expect, test } from "bun:test";
+import { inferOffExchangeFlag } from "../src/adapters/alpaca";
+
+describe("alpaca equities adapter helpers", () => {
+  test("inferOffExchangeFlag tags FINRA/TRF venues as off-exchange", () => {
+    const map = new Map<string, string>([
+      ["D", "FINRA / Nasdaq TRF"],
+      ["N", "FINRA / NYSE TRF"],
+      ["Q", "NASDAQ"],
+      ["P", "NYSE ARCA"],
+      ["O", "OTC Markets"]
+    ]);
+
+    expect(inferOffExchangeFlag("D", map)).toBe(true);
+    expect(inferOffExchangeFlag("N", map)).toBe(true);
+    expect(inferOffExchangeFlag("O", map)).toBe(true);
+    expect(inferOffExchangeFlag("Q", map)).toBe(false);
+    expect(inferOffExchangeFlag("P", map)).toBe(false);
+  });
+
+  test("inferOffExchangeFlag falls back conservatively when no mapping", () => {
+    const empty = new Map<string, string>();
+
+    expect(inferOffExchangeFlag(undefined, empty)).toBe(false);
+    expect(inferOffExchangeFlag("", empty)).toBe(false);
+    expect(inferOffExchangeFlag("D", empty)).toBe(true);
+    expect(inferOffExchangeFlag("N", empty)).toBe(false);
+  });
+});