feat(setup): clearer "Open Telegram" copy + mobile fallback hint

Two friction points in the Telegram channel's "Open Telegram" card,
both surfaced when running setup on a VM-via-SSH where the user's
local laptop has no Telegram client installed:

1. The opening sentence read "Opening @yourbot in Telegram so it's
   ready when the pairing code shows up." On a headless device that's
   misleading — nothing is auto-opened, the user has to click the
   link or use their phone. Rewrite as a direct, action-led
   instruction on the headless flow only:

     Open @yourbot in Telegram now — the pairing code is coming next,
     and that's where you'll send it.

   Plus a "Get started: <url>" line and a full-strength mobile
   fallback hint inside the card so headless users have all
   self-serve options visible.

   On non-headless the original status-style line stays accurate
   (`xdg-open` / `open` does fire for users with Telegram desktop
   installed), so the card stays a single line.

2. Clicking `https://t.me/yourbot` silently fails when the user's
   local device has no Telegram client. Non-headless gains:
     - a "(must be installed here)" qualifier on the confirm prompt
       so users without Telegram desktop know up-front;
     - a single combined dim fallback line below the prompt:
         "If browser does not appear, please visit: <url> — or
         search for @yourbot on your mobile."

   Direct `p.confirm` + `openUrl` instead of `confirmThenOpen` for
   the non-headless branch so we control the dim line fully (single
   combined line vs the helper's default URL-only line).

Headless layout drives the same self-serve content via the card body
itself; no confirm prompt fires there.

setup/channels/telegram.ts

@@ -21,7 +21,8 @@ import * as p from '@clack/prompts';
 import k from 'kleur';
 
 import * as setupLog from '../logs.js';
-import { confirmThenOpen, formatNoteLink } from '../lib/browser.js';
+import { openUrl } from '../lib/browser.js';
+import { isHeadless } from '../platform.js';
 import { askOperatorRole } from '../lib/role-prompt.js';
 import {
   type Block,
@@ -48,14 +49,37 @@ export async function runTelegramChannel(displayName: string): Promise<void> {
   // installed, or the bot's web profile if not. tg://resolve?domain= is
   // more direct but silently fails when the scheme isn't registered.
   const botUrl = `https://t.me/${botUsername}`;
+  // Two card variants — auto-open fires only on GUI, so headless users
+  // need full self-serve instructions inside the card itself, while GUI
+  // users get a leaner status line plus the auto-open + a single
+  // combined dim fallback line (URL + mobile alternative) on the
+  // confirm prompt below.
+  if (isHeadless()) {
     note(
       [
-      `Opening @${botUsername} in Telegram so it's ready when the pairing code shows up.`,
+        `Open @${botUsername} in Telegram now — the pairing code is coming next, and that's where you'll send it.`,
-      formatNoteLink(botUrl),
+        '',
-    ].filter((line): line is string => line !== null).join('\n'),
+        `Get started: ${botUrl}`,
+        '',
+        `Don't have Telegram installed here? Open it on any device and search for @${botUsername}`,
+      ].join('\n'),
       'Open Telegram',
     );
-  await confirmThenOpen(botUrl, 'Press Enter to open Telegram');
+  } else {
+    note(
+      `Opening @${botUsername} in Telegram so it's ready when the pairing code shows up.`,
+      'Open Telegram',
+    );
+    ensureAnswer(
+      await p.confirm({
+        message: `Press Enter to open Telegram (must be installed here)\n${k.dim(
+          `If browser does not appear, please visit: ${botUrl} — or search for @${botUsername} in Telegram`,
+        )}`,
+        initialValue: true,
+      }),
+    );
+    openUrl(botUrl);
+  }
 
   const install = await runQuietChild(
     'telegram-install',