refactor(pty): rename model-facing tools to terminal_* and harden teardown

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.

packages/pty/tool-pty/src/render.ts

@@ -1,4 +1,4 @@
-/** Model and ACP rendering for persistent PTY tool results. */
+/** Model and ACP rendering for persistent terminal tool results. */
 
 import type { PtyReadResult, PtySendRead, PtySendResult, PtySessionSnapshot, PtySpawnResult } from '@deepseek-ai/dsh-pty'
 
@@ -9,7 +9,7 @@ import type { PtyReadResult, PtySendRead, PtySendResult, PtySessionSnapshot, Pty
  */
 export function renderSpawn(result: PtySpawnResult): string {
   const label = result.name === undefined ? result.sessionId : `${result.sessionId} (${result.name})`
-  return `started PTY session ${label} [type: ${result.type}]\n${result.motd || '(no startup output)'}`
+  return `started terminal session ${label} [type: ${result.type}]\n${result.motd || '(no startup output)'}`
 }
 
 /**
@@ -50,7 +50,7 @@ export function renderRead(result: PtyReadResult): string {
  * @returns One line per session or the empty marker.
  */
 export function renderList(sessions: PtySessionSnapshot[]): string {
-  if (sessions.length === 0) return '(no PTY sessions)'
+  if (sessions.length === 0) return '(no terminal sessions)'
   return sessions.map((session) => {
     const name = session.name === undefined ? '' : ` (${session.name})`
     const pid = session.pid === undefined ? '' : ` pid=${session.pid}`