Document that package.json aliases may target only direct subfolders of src (#21)

Follow-up to #20, which was merged before this landed.

bot-agents has no `package.json` `imports` aliases (`src/` is flat and everything imports relatively), so no code changes. This records the new rule in the docs:

- `.agents/memory/imports-aliases-barrels.md`: aliases may target only a direct subfolder of `src/` (its `index.ts` or a `#x/*` pattern); nothing outside `src/`, not `src/` itself, not deeper folders; such code imports relatively.
- `.agents/memory/tests-layout-vitest.md`: `tests/` reach the public entry through a relative import, not a `#plugin` alias.
- `.agents/skills/migrate-deno-repo/SKILL.md` and `AGENTS.md`: same rule.

`vp check`, `vp test`, and `damem doctor` pass.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Reviewed-on: #21
Reviewed-by: bot <noreply@capsulizers.com>
Co-authored-by: Danny Kim <temeddix@gmail.com>
Co-committed-by: Danny Kim <temeddix@gmail.com>

.agents/memory/bot-agents-tests-root-only.md

@@ -4,7 +4,7 @@ description: Isolation and credential tests need root and use test.skipIf(!IS_RO
 
 Some tests exercise real UID isolation, process cleanup, and `prepare.ts`
 credential cleanup. They need root and are written as
-`test.skipIf(!IS_ROOT)(...)` (`IS_ROOT` from `src/testing.ts`), so they show
+`test.skipIf(!IS_ROOT)(...)` (`IS_ROOT` from `#testing`), so they show
 as skipped instead of silently passing.
 
 - As a normal user `vp test` passes 56 and skips 5. In CI (self-hosted
@@ -17,6 +17,9 @@ as skipped instead of silently passing.
   `codex`/`claude`/`npx` binaries and a fake Gitea through
   `protect-source.sh` -> `prepare.ts` -> `run.ts` -> `post.ts`; repeat that
   for changes to the phase flow ([[bot-agents-runtime-no-build]]).
-- `src/testing.ts` holds the shared test helpers; tests follow
+- `src/testing/index.ts` holds the shared test helpers (user IDs, temp dirs,
+  `runCommand`) behind the `#testing` alias. Every test imports it as
+  `#testing`. It imports no source module, so `tests/` (which may not use
+  `../`) never reaches internals. Tests follow
   [[tests-layout-vitest]] (unit tests in `src/*.test.ts`, repo-level ones in
   `tests/`).