docs(acp): RFC for the terminal-card rendering (implemented design)

Records the verified design before implementing: keep dsh-bash agent-side
execution and render Zed's terminal tool-call card via the `_meta` convention
(terminal_info/terminal_output/terminal_exit), capability-gated on
clientCapabilities._meta.terminal_output, with the ```console text block as the
no-capability fallback. Rejects the spec's client-side terminal/create path (it
would bypass dsh-bash's sandbox/env-scrub/ownership/cwd). Studied
claude-agent-acp, codex-acp, and Zed's renderer to ground the wire contract.
Live streaming and command classification are noted as separate follow-ups.

docs/rfc/README.md

@@ -31,7 +31,6 @@ Do NOT write one for a mechanical or local choice (a variable name, a one-file r
 | [Multiplex concurrent ACP sessions over one connection](proposed/2026-06-14-acp-multi-session.md) | 2026-06-14 |
 | [Optional Code Mode — model writes TypeScript against an SDK of all tools](proposed/2026-06-15-optional-code-mode.md) | 2026-06-15 |
 | [Runtime schemas for the event vocabulary (Zod vs the merge-extensible-map pattern)](proposed/2026-06-16-typed-event-schemas.md) | 2026-06-16 |
-| [Rich ACP bash rendering — the terminal sub-protocol and command classification](proposed/2026-06-18-acp-terminal-and-tool-rendering.md) | 2026-06-18 |
 
 ## Implemented
 
@@ -56,6 +55,7 @@ Do NOT write one for a mechanical or local choice (a variable name, a one-file r
 | [Session persistence as an abstract service over `SessionEvent`](implemented/2026-06-14-session-persistence.md) | 2026-06-14 |
 | [Every session event is enclosed in a turn](implemented/2026-06-15-turn-enclosure-invariant.md) | 2026-06-15 |
 | [pnpm as the package manager instead of Yarn 4](implemented/2026-06-16-pnpm-over-yarn.md) | 2026-06-16 |
+| [Rich ACP bash rendering — the terminal card (`_meta`) and command classification](implemented/2026-06-18-acp-terminal-and-tool-rendering.md) | 2026-06-18 |
 
 ## Rejected