docs(test): name the real reason the suite could reach ~/.codeman

#356 stopped a bare suite run from overwriting the production
`remote-hosts.json` by pointing `CODEMAN_DATA_DIR` at a throwaway dir, and it
gated every case-tree delete on the temp HOME. Both changes are right; the
explanation written next to them is not. It says `os.homedir()` reads
/etc/passwd rather than `$HOME` on Linux, which would mean the temp HOME in
test/setup.ts never worked. It does: libuv checks the env var before the passwd
entry (measured: `HOME=/tmp/x node -e 'console.log(os.homedir())'` prints
/tmp/x), and CLAUDE.md's testing section relies on exactly that.

What bypasses the temp HOME is `CODEMAN_DATA_DIR` itself. `getDataDir()` reads
it as an absolute override before it looks at `homedir()`, so one inherited from
the shell (a second instance, a beta run) sends the whole suite at the real data
dir. That is the case setup.ts now closes, and #371 names the same variable from
the other direction.

The comments in setup.ts, the `safeRmHomeTree` helper, the voice-routes and
case-clone tests now say that, and the containment gate is described as what it
is: defense in depth. CLAUDE.md's testing paragraph gets the same note so the
next reader does not chase a homedir() bug that does not exist.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Qg6bcATm1pNNY4kQWGwzgu

CLAUDE.md

@@ -407,7 +407,7 @@ Raw `npx vitest` skips the config (and with it `setup.ts`); always use `npm test
 
 **Config**: Vitest with `globals: true`, `fileParallelism: false`. Timeout 30s, teardown 60s. `config/vitest.config.ts` is the everything-config behind `test:all`; `config/vitest.ci.config.ts` is the gate and derives its excludes from `config/test-suites.ts`, which is also what `vitest.browser.config.ts` and `vitest.perf.config.ts` derive their includes from — so the exclusions and the runners cannot drift apart. Keep shared options in sync across them.
 
-**Tmux safety**: under vitest (`VITEST` env var, set automatically), `TmuxManager` no-ops ALL shell commands and becomes a pure in-memory mock — tests physically cannot create/kill/attach real tmux sessions (`IS_TEST_MODE` in `src/tmux-manager.ts`). Every docker IO path is no-op'd the same way. `Session` is test-gated too: instead of attaching a real tmux client, it spawns a raw-mode echo PTY (`TEST_PTY_SCRIPT` in `src/session.ts`), so integration tests get a live input/output loop that echoes each byte exactly once. `test/setup.ts` gives every test file a temporary `HOME`/`USERPROFILE` (all `homedir()`-derived state, `~/.codeman` and `~/codeman-cases` included, resolves into a per-file fixture; the Playwright browser cache path is preserved), and additionally strips `CODEMAN_PASSWORD`/`CODEMAN_USERNAME` (so auth state from the running instance can't leak into tests) and `CODEMAN_GESTURE` (a shell-exported gesture flag would flip render-injection assertions). ⚠️ Raw `npx vitest` without `--config` skips `setup.ts` and with it the temp-HOME isolation.
+**Tmux safety**: under vitest (`VITEST` env var, set automatically), `TmuxManager` no-ops ALL shell commands and becomes a pure in-memory mock — tests physically cannot create/kill/attach real tmux sessions (`IS_TEST_MODE` in `src/tmux-manager.ts`). Every docker IO path is no-op'd the same way. `Session` is test-gated too: instead of attaching a real tmux client, it spawns a raw-mode echo PTY (`TEST_PTY_SCRIPT` in `src/session.ts`), so integration tests get a live input/output loop that echoes each byte exactly once. `test/setup.ts` gives every test file a temporary `HOME`/`USERPROFILE` (all `homedir()`-derived state, `~/.codeman` and `~/codeman-cases` included, resolves into a per-file fixture; the Playwright browser cache path is preserved), and additionally strips `CODEMAN_PASSWORD`/`CODEMAN_USERNAME` (so auth state from the running instance can't leak into tests) and `CODEMAN_GESTURE` (a shell-exported gesture flag would flip render-injection assertions), and points `CODEMAN_DATA_DIR` at a throwaway dir (#356). ⚠️ That last one is what actually protects `~/.codeman`: `getDataDir()` reads `CODEMAN_DATA_DIR` as an ABSOLUTE override before it ever looks at `homedir()`, so one inherited from the shell (a second instance, a beta run) bypasses the temp HOME entirely, and a bare suite run once overwrote the real `remote-hosts.json` with a route test's fixture. `os.homedir()` itself DOES follow `$HOME`, so the temp HOME is what redirects everything else. Tests that delete case trees go through `safeRmHomeTree()` (`test/mocks`), which refuses any path outside the temp HOME, so a wrong anchor leaves a temp dir behind instead of deleting `~/codeman-cases`. ⚠️ Raw `npx vitest` without `--config` skips `setup.ts` and with it the temp-HOME isolation.
 
 **Ports**: Pick unique ports manually, 3150+. Search `const PORT =` before adding new tests. Never 3000 (the live instance).