Move tests out of src/ into a top-level tests/ directory

src/ now contains only source code; tests live alongside it under
tests/. Bun's test runner discovers '**/*.test.ts' so no test-runner
config change is needed.

Changes:
  - tests/config.test.ts        (was src/config.test.ts)
  - tests/configFile.test.ts    (was src/configFile.test.ts)
  - Imports updated: ./config.ts -> ../src/config.ts (likewise for
    configFile.ts and errors.ts).
  - tsconfig.json include adds 'tests/**/*.ts' so tsc type-checks
    the test files too.

All 25 tests still pass; tsc clean.

tests/config.test.ts

@@ -7,9 +7,9 @@
 
 import { afterEach, beforeEach, describe, expect, test } from "bun:test";
 
-import { DEFAULT_CONFIG, defaultConfigPath, resolveConfig } from "./config.ts";
-import type { ConfigOverrides } from "./config.ts";
-import { CliError } from "./errors.ts";
+import { DEFAULT_CONFIG, defaultConfigPath, resolveConfig } from "../src/config.ts";
+import type { ConfigOverrides } from "../src/config.ts";
+import { CliError } from "../src/errors.ts";
 
 const NONE: ConfigOverrides = {
     moveInterval: undefined,

tests/configFile.test.ts

@@ -10,8 +10,8 @@ import { mkdtempSync, rmSync, writeFileSync } from "node:fs";
 import { tmpdir } from "node:os";
 import { join } from "node:path";
 
-import { loadConfigFile } from "./configFile.ts";
-import { CliError } from "./errors.ts";
+import { loadConfigFile } from "../src/configFile.ts";
+import { CliError } from "../src/errors.ts";
 
 let TMP: string;
 

tsconfig.json

@@ -12,5 +12,5 @@
     "resolveJsonModule": true,
     "noUncheckedIndexedAccess": true
   },
-  "include": ["src/**/*.ts"]
+  "include": ["src/**/*.ts", "tests/**/*.ts"]
 }