Rename the six model-facing tools pty_* -> terminal_* and align every
description, guidance section, ACP card title, and rendered result to
terminal terminology. Package and service internals keep their technical
PTY names (PtyService, "unknown PTY session", node-pty).
Harden the local backend teardown:
- a failed close is retryable: drop the memoized rejection so a later
terminal_close re-runs against the live process table
- service disposal clears the backend, reservation, and owner-cleanup
registries even when a close fails
- stop readiness polling before teardown so an in-flight send settles as
session_exit instead of a mis-inferred wait reason
- bound the sanitizer's pending buffer against unterminated escape runs
Update the tool catalog, package READMEs, the bilingual Agent Note, and the
acp/headless pty-tools snapshots to match.
