feat(acp): render bash as a terminal card via the _meta convention

When the client advertises clientCapabilities._meta.terminal_output (Zed), a
bash tool call now renders as a real TERMINAL card — a cwd header + the command
+ its output — instead of the plain ```console text block. Keeps agent-side
dsh-bash execution; rejects the spec's client-side terminal/create (which would
bypass sandbox/env-scrub/ownership/cwd). Matches what claude-agent-acp and
codex-acp do; wire contract verified against Zed's source.

- dsh-tools: a provider-neutral ToolTerminal shape ({ cwd?, output? }) on
  ToolCallPresentation/ToolResultPresentation — a tool asks "render me as a
  terminal"; no ACP types leak in.
- dsh-tool-bash: bash presentCall marks terminal (cwd from an explicit absolute
  workdir, else left for the bridge to fill from the session cwd); presentResult
  carries the output alongside the ```console fallback.
- dsh-acp: initialize reads/remembers the _meta.terminal_output capability;
  streamSessionEventUpdate maps a terminal presentation to
  content:[{type:'terminal',terminalId}] + _meta.terminal_info on the call and
  _meta.terminal_output on the update WHEN capable — else the unchanged text
  path. terminalId is the callId; cwd defaults to the session header. The pure
  translator gained a TerminalRendering {enabled,cwd} param (off by default).

Tests via the REAL tool-bash + bash-local: capability ON -> terminal content +
_meta; OFF -> no _meta (text path). The with-key e2e adds a real-model terminal
card case (echo over ACP with the capability on). 773 tests, 100% coverage.

The exit-status pill (_meta.terminal_exit), live streaming
(_meta.terminal_output_delta), and command classification are RFC follow-ups.

packages/tools/README.md

@@ -72,8 +72,8 @@ See `defineTool`, `validateArgs`, `ToolArgsError`, `SchemaSpec`, `InferArgs`, an
 
 A tool owns how ITS calls render in a UI (an editor's tool-call card, a CLI log line) — a UI plugin must NOT special-case tool names. A `ToolDefinition` may declare two optional, pure, display-only methods:
 
-- `presentCall(args): ToolCallPresentation | undefined` — the PENDING state: a human-readable `title` (always-visible label), an optional `kind` (`read`/`edit`/`execute`/… for icon/treatment, default `other`), and an optional `rawInput` (the salient input to show in a detail view — e.g. a shell command as a string, NOT the whole args object).
-- `presentResult(args, result): ToolResultPresentation | undefined` — the COMPLETED state, given the same `args` and the `{ content, isError }` result: an optional replacement `title` and reformatted `content` (e.g. wrap command output in a fenced ` ```console ` block — a UI-only affordance that must NOT appear in the model-facing `execute` result).
+- `presentCall(args): ToolCallPresentation | undefined` — the PENDING state: a human-readable `title` (always-visible label), an optional `kind` (`read`/`edit`/`execute`/… for icon/treatment, default `other`), an optional `rawInput` (the salient input to show in a detail view — e.g. a shell command as a string, NOT the whole args object), and an optional `terminal` (a neutral `{ cwd? }` asking a capable UI to render this call as a TERMINAL, e.g. for `bash`).
+- `presentResult(args, result): ToolResultPresentation | undefined` — the COMPLETED state, given the same `args` and the `{ content, isError }` result: an optional replacement `title`, reformatted `content` (e.g. wrap command output in a fenced ` ```console ` block — a UI-only affordance that must NOT appear in the model-facing `execute` result), and an optional `terminal` (the `{ output? }` for a terminal-rendered call). The `ToolTerminal` shape is provider-neutral; a UI bridge (the ACP bridge) maps it to a terminal card and a UI that can't ignores it and uses `content`.
 
 Returning `undefined` (or omitting a method) tells a UI to fall back to a generic presentation (title = tool name, raw args as input, raw result content). Both methods must be **pure and side-effect-free**: a UI may call them during live streaming AND during a session-log replay, so they depend only on their arguments. With `defineTool`, `args` is the typed `InferArgs<S>` shape; the helper soft-validates before calling (a malformed/older logged arg shape yields `undefined` rather than throwing, since display must never crash a replay). The shapes are provider-neutral — the ACP bridge (`dsh-acp`) maps them to ACP `tool_call`/`tool_call_update` wire fields, and `dsh-tool-bash` is the reference implementation.