fix(test): strip the instance-selection env vars in test/setup.ts

[opticon454]

test/setup.ts gives every test file a temp HOME so the suite cannot touch the real Codeman tree, and strips the env vars that would leak past it — but the list only covered auth and the gesture flag. The three vars src/config/instance.ts derives the data dir and tmux socket from were missing, and they reach past the temp HOME:

• CODEMAN_DATA_DIR is the one that matters. It is an ABSOLUTE override read in getDataDir(), so it bypasses HOME entirely: a developer who exports it — or a shell left over from codeman web -d — has the suite reading and WRITING their real state.json, users.json, intents.json and hook-secret.
• CODEMAN_INSTANCE moves the data dir to ~/.codeman-<name> and the socket to codeman-<name>. Inside the temp HOME that is not data loss, but it silently changes the paths tests assert on — and scripts/run-beta.sh exports it, so any shell that has run a beta carries it.
• CODEMAN_TMUX_SOCKET renames the socket resolveTmuxSocketName() returns. TmuxManager no-ops its shell commands under vitest, so this is assertion drift rather than a stray tmux -L against prod — same class of leak, same one-line fix.

They are deleted in the setup file rather than in a hook because CODEMAN_INSTANCE is captured into a module-level const the first time config/instance.ts is imported; a beforeEach would already be too late.

test/test-env-isolation.test.ts pins the whole list in two halves, because the obvious half is not enough: asserting the vars are unset passes trivially on a machine that never set them, so a removed delete line would sail through on almost every box and on CI. The static half reads setup.ts and asserts each name is deleted there, which fails everywhere. An anti-drift check catches the other direction — a var stripped in setup.ts but never given a reason in the list — and is scoped to the strip section so the teardown's restores are not mistaken for strips.

Verified by demonstrating the leak: with the CODEMAN_DATA_DIR line removed and the var exported, the runtime assertion fails; with the line restored it passes. Full suite: no new failures against an upstream/master baseline.

[opticon454]

As found/mentioned in #347

[Ark0N]

Merged, thank you. The static half of the test is the right call and it is what kept this honest once #356 landed next to it: that PR had answered the same leak by pointing CODEMAN_DATA_DIR at a second throwaway dir, so the plain merge set the variable and deleted it a few lines later. I resolved it in favour of your strip (72fd231): the second directory, its restores and the vitest config env entries are gone, getDataDir() lands under the temp HOME like everything else, and CLAUDE.md's testing paragraph now names the three variables and why CODEMAN_INSTANCE has to go in the setup file rather than a hook. Test-only, so it rides the next release rather than getting one of its own.