feat(cli): add --title flag to set tab title when summoning

Add a --title <title> flag to the dispatch CLI so a summoned agent's
conversation/tab gets a human-readable title at creation time instead of the
auto-derived default (Untitled until the first message append).

The title is carried as an additive optional ChatRequest.title field (the
HTTP client-server contract), parsed + trimmed server-side in parseChatBody,
and persisted via the conversation store's setConversationTitle in the POST
/chat route BEFORE the turn starts — so the title is set atomically with
creation and before --open signals the frontend to open the tab. No second
HTTP round-trip is needed.

A whitespace-only title is treated as absent (auto-derive); a non-string
title yields HTTP 400. A title-set failure is logged but never blocks the
turn (the title is a nicety, the answer is not). The change is purely
additive — no existing behavior or assertion changes.

Verification: typecheck EXIT 0; test 2021 passed | 6 skipped | 0 failed;
check EXIT 0 (12 pre-existing warnings in untouched files).

1 files changed, 7 insertions, 0 deletions

diff --git a/packages/cli/src/args.ts b/packages/cli/src/args.ts
index 52f1fba..581d4c2 100644
--- a/packages/cli/src/args.ts
+++ b/packages/cli/src/args.ts
@@ -27,6 +27,7 @@ export type ParsedCommand =
       readonly showReasoning: boolean;
       readonly open: boolean;
       readonly workspaceId?: string | undefined;
+      readonly title?: string | undefined;
     }
   | {
       readonly kind: "list";
@@ -307,6 +308,7 @@ export function parseArgs(argv: readonly string[], opts: ParseOpts): ParsedComma
   let open = false;
   let server = opts.defaultServer;
   let workspaceId: string | undefined;
+  let title: string | undefined;
 
   for (let i = 1; i < argv.length; i++) {
     const arg = argv[i] as string;
@@ -338,6 +340,10 @@ export function parseArgs(argv: readonly string[], opts: ParseOpts): ParsedComma
       case "--open":
         open = true;
         break;
+      case "--title":
+        if (i + 1 >= argv.length) return { kind: "error", message: "--title requires a value" };
+        title = argv[++i];
+        break;
       case "--effort":
         if (i + 1 >= argv.length)
           return {
@@ -383,5 +389,6 @@ export function parseArgs(argv: readonly string[], opts: ParseOpts): ParsedComma
     showReasoning,
     open,
     ...(workspaceId !== undefined && { workspaceId }),
+    ...(title !== undefined && { title }),
   };
 }