feat(setup): switch elapsed-time suffixes to "Xm Ys" past 60s

Adds a `fmtDuration(ms)` helper in `setup/lib/theme.ts` that returns
`47s` under a minute and `1m 34s` from 60s onward, then routes every
elapsed-time spinner suffix in the setup flow through it. Replaces
the inline `Math.round((Date.now() - start) / 1000)` + `(${elapsed}s)`
pattern at every site.

Format is consistent past 60s — `1m 0s` over `1m` — so the live
spinner doesn't change shape at every whole-minute crossing.

Sites updated: setup/auto.ts, setup/lib/{runner,tz-from-claude,
claude-assist}.ts, and setup/channels/{signal,whatsapp,telegram,
discord,slack}.ts. Pre-allocated suffix budgets in `fitToWidth`
calls bumped from `' (999s)'` to `' (99m 59s)'` so long-running
steps don't blow past the reserved width.

setup/channels/whatsapp.ts

@@ -46,7 +46,7 @@ import {
   writeStepEntry,
 } from '../lib/runner.js';
 import { askOperatorRole } from '../lib/role-prompt.js';
-import { accentGreen, brandBody, brandBold, note } from '../lib/theme.js';
+import { accentGreen, brandBody, brandBold, fmtDuration, note } from '../lib/theme.js';
 
 const DEFAULT_AGENT_NAME = 'Nano';
 const AUTH_CREDS_PATH = path.join(process.cwd(), 'store', 'auth', 'creds.json');
@@ -379,8 +379,7 @@ async function restartService(): Promise<void> {
     // Give the adapter a moment to reconnect before init-first-agent's
     // welcome DM hits the delivery path.
     await new Promise((r) => setTimeout(r, 5000));
-    const elapsed = Math.round((Date.now() - start) / 1000);
-    s.stop(`NanoClaw restarted. ${k.dim(`(${elapsed}s)`)}`);
+    s.stop(`NanoClaw restarted. ${k.dim(`(${fmtDuration(Date.now() - start)})`)}`);
     setupLog.step('whatsapp-restart', 'success', Date.now() - start, {
       PLATFORM: platform,
     });