docs: prose-standard pass over the PR's added comments and one label

Current-state fixes: two test comments still named the pre-rename
spawnProcess; two narrated history ('the old whole-chunk drop', 'no
longer kills backend work') instead of the pinned contract; and the
packages/README row said process-group where the seam's own vocabulary
is process-tree (en+zh, pair re-recorded).

packages/bash/bash-local/tests/executor.spec.ts

@@ -309,7 +309,7 @@ describe('process lifecycle ownership (the subprocess service, not the executor)
     const pid = Number((await readUntil(proc, '\n')).trim())
     expect(Number.isInteger(pid) && pid > 0).toBe(true)
 
-    // Reloading/disposing the executor no longer kills backend work — the
+    // Executor reload/disposal leaves background work running — the
     // handle stays live and readable, mirroring the task runtime's
     // registrations-outlive-producer-fibers contract.
     await executorFiber.dispose()