feat(cli): add --workspace filter to 'dispatch list'

The backend already supported GET /conversations?workspaceId= but the CLI
never sent it. Wire the list command to that filter:

- args.ts: parse --workspace / -w on 'list' (placed before the --catch-all
  so the single-dash -w shorthand isn't taken for a positional prefix);
  add workspaceId? to the list ParsedCommand.
- http.ts: add workspaceId? to FetchConversationsOpts; send ?workspaceId=
  (after q/status, preserving URLSearchParams order).
- main.ts: forward parsed.workspaceId into fetchConversations; update USAGE.

Composable with --status and the <prefix> short-id arg. 'Open conversations
in workspace X' is now: dispatch list --workspace X  (status defaults to
active,idle). No contract changes — purely additive CLI wiring.

Tests: +4 args (incl. composability + missing-value error), +2 http
(exact ?workspaceId= URL + combined status/workspaceId with %2C encoding).
typecheck EXIT 0, biome clean (364 files), full suite 1558 passed.
Live-verified against an isolated server.

1 files changed, 30 insertions, 0 deletions

diff --git a/packages/cli/src/http.test.ts b/packages/cli/src/http.test.ts
index 2aa61e9..ab39813 100644
--- a/packages/cli/src/http.test.ts
+++ b/packages/cli/src/http.test.ts
@@ -289,6 +289,36 @@ describe("fetchConversations", () => {
 		expect(calledUrl).toBe("http://localhost:24203/conversations?q=abc+def");
 	});
 
+	it("appends ?workspaceId=<value> when a workspaceId is given", async () => {
+		let calledUrl: string | undefined;
+		const fakeFetch = (async (url: string | URL | Request): Promise<Response> => {
+			calledUrl = String(url);
+			return new Response(JSON.stringify({ conversations: [] }), { status: 200 });
+		}) as unknown as typeof fetch;
+
+		await fetchConversations(
+			{ fetchImpl: fakeFetch },
+			{ server: "http://localhost:24203", workspaceId: "proj" },
+		);
+		expect(calledUrl).toBe("http://localhost:24203/conversations?workspaceId=proj");
+	});
+
+	it("combines ?status= and ?workspaceId= when both are given", async () => {
+		let calledUrl: string | undefined;
+		const fakeFetch = (async (url: string | URL | Request): Promise<Response> => {
+			calledUrl = String(url);
+			return new Response(JSON.stringify({ conversations: [] }), { status: 200 });
+		}) as unknown as typeof fetch;
+
+		await fetchConversations(
+			{ fetchImpl: fakeFetch },
+			{ server: "http://localhost:24203", status: "active,idle", workspaceId: "proj" },
+		);
+		expect(calledUrl).toBe(
+			"http://localhost:24203/conversations?status=active%2Cidle&workspaceId=proj",
+		);
+	});
+
 	it("throws on non-OK status", async () => {
 		const fakeFetch = (async (): Promise<Response> =>
 			new Response("boom", { status: 500 })) as unknown as typeof fetch;