Add comprehensive test suite with CI workflow

- 211 tests across 15 files covering services (tracking, discovery,
  metadata, backup, credits, webhooks, settings, update-check, colors,
  person), utilities (config, cron, providers, title-theme), and TMDB
  image URL helpers
- `lib/test-preload.ts` + `bunfig.toml` wire up a global in-memory
  SQLite DB with migrations for all DB-backed tests
- `lib/test-utils.ts` provides `clearAllTables()` and seed helpers
  (insertUser, insertTitle, insertTvShow, insertMovieWatch, etc.)
- Export `getBackupSource`, `isKnownBackup`, `isValidBackupFilename`,
  `buildBackupCron`, `performUpdateCheck` internals for direct testing
- GitHub Actions workflow runs `bun test --coverage` on push/PR to main

lib/services/backup.test.ts

@@ -0,0 +1,101 @@
+import { describe, expect, test } from "bun:test";
+
+import {
+  getBackupSource,
+  isKnownBackup,
+  isValidBackupFilename,
+} from "./backup";
+
+describe("getBackupSource", () => {
+  test("detects manual backup", () => {
+    expect(getBackupSource("sofa-manual-2024-01-15-120000.db")).toBe("manual");
+  });
+
+  test("detects manual backup with milliseconds", () => {
+    expect(getBackupSource("sofa-manual-2024-01-15-120000123.db")).toBe(
+      "manual",
+    );
+  });
+
+  test("detects scheduled backup", () => {
+    expect(getBackupSource("sofa-scheduled-2024-06-01-030000.db")).toBe(
+      "scheduled",
+    );
+  });
+
+  test("detects pre-restore backup", () => {
+    expect(getBackupSource("pre-restore-2024-06-01-030000.db")).toBe(
+      "pre-restore",
+    );
+  });
+
+  test("defaults to manual for unknown patterns", () => {
+    expect(getBackupSource("random-file.db")).toBe("manual");
+  });
+});
+
+describe("isKnownBackup", () => {
+  test("recognizes manual backup", () => {
+    expect(isKnownBackup("sofa-manual-2024-01-15-120000.db")).toBe(true);
+  });
+
+  test("recognizes scheduled backup", () => {
+    expect(isKnownBackup("sofa-scheduled-2024-06-01-030000.db")).toBe(true);
+  });
+
+  test("recognizes pre-restore backup", () => {
+    expect(isKnownBackup("pre-restore-2024-06-01-030000.db")).toBe(true);
+  });
+
+  test("recognizes backup with milliseconds", () => {
+    expect(isKnownBackup("sofa-manual-2024-01-15-120000456.db")).toBe(true);
+  });
+
+  test("rejects random filename", () => {
+    expect(isKnownBackup("random-file.db")).toBe(false);
+  });
+
+  test("rejects similar but wrong prefix", () => {
+    expect(isKnownBackup("sofa-auto-2024-01-15-120000.db")).toBe(false);
+  });
+
+  test("rejects wrong extension", () => {
+    expect(isKnownBackup("sofa-manual-2024-01-15-120000.sql")).toBe(false);
+  });
+});
+
+describe("isValidBackupFilename", () => {
+  test("accepts valid manual backup", () => {
+    expect(isValidBackupFilename("sofa-manual-2024-01-15-120000.db")).toBe(
+      true,
+    );
+  });
+
+  test("accepts valid scheduled backup", () => {
+    expect(isValidBackupFilename("sofa-scheduled-2024-06-01-030000.db")).toBe(
+      true,
+    );
+  });
+
+  test("rejects path traversal", () => {
+    expect(isValidBackupFilename("../sofa-manual-2024-01-15-120000.db")).toBe(
+      false,
+    );
+  });
+
+  test("rejects directory separators", () => {
+    expect(
+      isValidBackupFilename("subdir/sofa-manual-2024-01-15-120000.db"),
+    ).toBe(false);
+  });
+
+  test("rejects unknown filenames", () => {
+    expect(isValidBackupFilename("evil.db")).toBe(false);
+  });
+
+  test("rejects filenames with double dots", () => {
+    expect(isValidBackupFilename("sofa-manual-2024..01-15-120000.db")).toBe(
+      false,
+    );
+  });
+});