Route tests through a #testing alias, ban ../ imports, and document the alias ownership rule

tests/entrypoints.test.ts

@@ -3,7 +3,7 @@ import { fileURLToPath } from "node:url";
 
 import { expect, test } from "vite-plus/test";
 
-import { output } from "../src/command.ts";
+import { output } from "#testing";
 
 // Each phase runs as `node src/<phase>.ts` with no build step. Node loads the
 // whole import graph, stripping types, before the phase reads its first

tests/workflow.test.ts

@@ -4,11 +4,8 @@ import process from "node:process";
 import { assert, expect, test } from "vite-plus/test";
 import { parse } from "yaml";
 
-import { output } from "../src/command.ts";
-import { isNotFound } from "../src/errors.ts";
-import { isMapping } from "../src/json.ts";
-import type { JsonObject } from "../src/json.ts";
-import { makeTempDir } from "../src/testing.ts";
+import { isMapping, isNotFound, makeTempDir, output } from "#testing";
+import type { JsonObject } from "#testing";
 
 const mapping = (value: unknown, at: string): JsonObject => {
   assert(isMapping(value), at);