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.

scripts/gen-tool-catalog.ts

@@ -232,7 +232,7 @@ const TOOL_PACKAGES: ToolPackage[] = [
       await ctx.plugin(ToolPty)
     },
     note:
-      'The six PTY tools are opt-in and complement one-shot bash/filesystem tools. `pty_send(run_in_background: true)` registers with `ctx.tasks`; TUI, named key sequences, BEL, resize, auto-start, and cross-agent sharing are absent from the schema.',
+      'The six terminal tools are opt-in and complement one-shot bash/filesystem tools. `terminal_send(run_in_background: true)` registers with `ctx.tasks`; TUI, named key sequences, BEL, resize, auto-start, and cross-agent sharing are absent from the schema.',
   },
   {
     pkg: '@deepseek-ai/dsh-tool-skill',