refactor(vscode): split tests out of src into sibling tests/ and e2e/ trees

[fi3ework]

What

Stacked on #6. Pure relocation — no test changed what it asserts.

The unit suites sat next to the modules they cover, so src/ (the tree that produces the published bundle) also held 17 test files and a text fixture, and the E2E harness sat one level deeper than it needed to. The package now has three siblings:

packages/vscode/
  src/     source only
  tests/   the Rstest unit suites, mirroring src/
  e2e/     the extension-host suites (tsc -> tests-dist/)

rstest.config.mts and tsconfig.json already named the destination, so the moves themselves were the easy half. The rest is everything that was depth-sensitive:

• Suite imports into src/ lose one .. in tests/, and one more in e2e/ (both trees came up a level).
• Every harness climbs one fewer level out of tests-dist/ — runTest.ts x3 and the rstest FIXTURES_ROOT each drop a .., and the compiled entry points move from tests-dist/tests/e2e/... to tests-dist/e2e/....
• Path literals and globs follow the trees: the package scripts, both tsconfigs, the Rstest include/exclude, the lint and fmt ignore globs in the root rstack.config.ts, the playground fixture list in .vscode/launch.json, and one CI comment.
• .gitignore kept fixture installs untracked through four rules under the old path. They stopped matching the moment the tree moved, which surfaced as fixture lockfiles turning up untracked; they now point at e2e/.

src/stacks/fmt/stubProcess.ts moves with the suites that use it — it was always test-only scaffolding, never a build entry. src/stacks/test/parse.fixture.txt moves for the same reason; it was the one non-.ts file under src/.

The second commit removes an include from tsconfig.e2e.json that pointed at src/shell/detection.ts and src/shell/types.ts, a path this package has never had. tsc ignores a non-matching include pattern when another one matches, so it was inert: the suites always reached those modules through their own imports.

Test plan

Every gate run locally against the new layout, with tests-dist/ deleted first so no stale compile could mask a broken path:

• pnpm lint — 0 errors, 0 type errors.
• pnpm test:unit — 19 files, 165 passing, the same set as before the move.
• pnpm build — clean.
• All four E2E harnesses exit 0, since each one's __dirname climb changed: test:e2e:smoke, test:e2e:vscode, test:e2e:rstest:run, test:e2e:lint:run (8 suites).

Fixture file contents are byte-identical — they were renamed, never rewritten, and the pre-commit rs fmt skips them through the ignore globs.

Checklist

• Tests updated (or not required).
• Documentation updated (or not required).

[chatgpt-codex-connector]

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