refactor(tests): move backend tests into src/backend/tests mirror tree

Backend *.test.ts files (and the test-support harness) no longer sit next
to source files; they live under src/backend/tests/ mirroring the source
layout. Imports rewritten accordingly; CLAUDE.md convention updated.

src/backend/tests/database/repositories/settings-repository.test.ts

@@ -0,0 +1,91 @@
+import { afterEach, describe, expect, it } from "vitest";
+import { TestSqliteDatabase } from "./test-support.js";
+import { SettingsRepository } from "../../../database/repositories/settings-repository.js";
+
+describe("SettingsRepository", () => {
+  let adapter: TestSqliteDatabase | null = null;
+
+  afterEach(async () => {
+    if (adapter) {
+      await adapter.close();
+      adapter = null;
+    }
+  });
+
+  async function createRepository(): Promise<SettingsRepository> {
+    adapter = new TestSqliteDatabase();
+    const context = await adapter.connect();
+    context.sqlite?.exec(`
+      CREATE TABLE settings (
+        key TEXT PRIMARY KEY,
+        value TEXT NOT NULL
+      )
+    `);
+    return new SettingsRepository(context);
+  }
+
+  it("creates and updates settings", async () => {
+    const repo = await createRepository();
+
+    await repo.set("allow_registration", "true");
+    expect(await repo.get("allow_registration")).toBe("true");
+
+    await repo.set("allow_registration", "false");
+    expect(await repo.get("allow_registration")).toBe("false");
+  });
+
+  it("lists and upserts settings", async () => {
+    const repo = await createRepository();
+
+    await repo.upsert("theme", "dark");
+    await repo.upsert("allow_registration", "true");
+    await repo.upsert("theme", "light");
+
+    expect(await repo.get("theme")).toBe("light");
+    expect(await repo.listAll()).toEqual(
+      expect.arrayContaining([
+        { key: "theme", value: "light" },
+        { key: "allow_registration", value: "true" },
+      ]),
+    );
+  });
+
+  it("returns null or fallback when setting is missing", async () => {
+    const repo = await createRepository();
+
+    expect(await repo.get("missing")).toBeNull();
+    expect(await repo.getBoolean("missing", true)).toBe(true);
+  });
+
+  it("reads boolean settings", async () => {
+    const repo = await createRepository();
+
+    await repo.set("enabled", "1");
+    await repo.set("disabled", "false");
+
+    expect(await repo.getBoolean("enabled")).toBe(true);
+    expect(await repo.getBoolean("disabled", true)).toBe(false);
+  });
+
+  it("deletes settings", async () => {
+    const repo = await createRepository();
+
+    await repo.set("theme", "dark");
+    await repo.delete("theme");
+
+    expect(await repo.get("theme")).toBeNull();
+  });
+
+  it("deletes settings by SQL LIKE pattern", async () => {
+    const repo = await createRepository();
+
+    await repo.set("user_kek_salt_user-1", "salt");
+    await repo.set("user_encrypted_dek_user-1", "dek");
+    await repo.set("user_kek_salt_user-2", "other");
+
+    expect(await repo.deleteLike("user_%_user-1")).toBe(2);
+    expect(await repo.get("user_kek_salt_user-1")).toBeNull();
+    expect(await repo.get("user_encrypted_dek_user-1")).toBeNull();
+    expect(await repo.get("user_kek_salt_user-2")).toBe("other");
+  });
+});