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, 35 insertions, 0 deletions

diff --git a/packages/cli/src/args.test.ts b/packages/cli/src/args.test.ts
index 7a45c02..e613f31 100644
--- a/packages/cli/src/args.test.ts
+++ b/packages/cli/src/args.test.ts
@@ -254,6 +254,41 @@ describe("parseArgs", () => {
 			});
 		});
 
+		it("parses 'list' with --workspace", () => {
+			expect(parseArgs(["list", "--workspace", "proj"], { defaultServer })).toEqual({
+				kind: "list",
+				server: "http://localhost:24203",
+				workspaceId: "proj",
+				all: false,
+			});
+		});
+
+		it("parses 'list' with -w shorthand", () => {
+			const result = parseArgs(["list", "-w", "ws"], { defaultServer });
+			expect(result.kind).toBe("list");
+			if (result.kind === "list") expect(result.workspaceId).toBe("ws");
+		});
+
+		it("parses 'list' with --workspace, --status, and a prefix together", () => {
+			const result = parseArgs(["list", "abc", "--status", "active", "--workspace", "proj"], {
+				defaultServer,
+			});
+			expect(result).toEqual({
+				kind: "list",
+				server: "http://localhost:24203",
+				query: "abc",
+				status: "active",
+				workspaceId: "proj",
+				all: false,
+			});
+		});
+
+		it("errors when --workspace has no value (list)", () => {
+			const result = parseArgs(["list", "--workspace"], { defaultServer });
+			expect(result.kind).toBe("error");
+			if (result.kind === "error") expect(result.message).toContain("--workspace requires a value");
+		});
+
 		it("parses 'list' with --all", () => {
 			expect(parseArgs(["list", "--all"], { defaultServer })).toEqual({
 				kind: "list",