refactor: extract duplicated utility functions into shared modules

Consolidate 20+ duplicate function definitions across UI components into
three shared util files (format-utils, agent-utils, config-draft-utils).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/src/pages/AgentHealth/AgentHealth.tsx

@@ -1,6 +1,6 @@
 import { useState, useMemo, useCallback } from 'react';
 import { useParams, useNavigate } from 'react-router';
-import { ExternalLink, RefreshCw, Pencil, UserPlus, UserMinus, Play, Square, Clock, Skull, HeartPulse, Route, Send, Activity } from 'lucide-react';
+import { ExternalLink, RefreshCw, Pencil } from 'lucide-react';
 import {
   StatCard, StatusDot, Badge, MonoText,
   GroupCard, DataTable, EventFeed,
@@ -13,31 +13,11 @@ import { useApplicationLogs } from '../../api/queries/logs';
 import { useApplicationConfig, useUpdateApplicationConfig } from '../../api/queries/commands';
 import type { ConfigUpdateResponse } from '../../api/queries/commands';
 import type { AgentInstance } from '../../api/types';
+import { timeAgo } from '../../utils/format-utils';
+import { formatUptime, mapLogLevel, eventSeverity, eventIcon } from '../../utils/agent-utils';
 
 // ── Helpers ──────────────────────────────────────────────────────────────────
 
-function timeAgo(iso?: string): string {
-  if (!iso) return '\u2014';
-  const diff = Date.now() - new Date(iso).getTime();
-  const secs = Math.floor(diff / 1000);
-  if (secs < 60) return `${secs}s ago`;
-  const mins = Math.floor(secs / 60);
-  if (mins < 60) return `${mins}m ago`;
-  const hours = Math.floor(mins / 60);
-  if (hours < 24) return `${hours}h ago`;
-  return `${Math.floor(hours / 24)}d ago`;
-}
-
-function formatUptime(seconds?: number): string {
-  if (!seconds) return '\u2014';
-  const days = Math.floor(seconds / 86400);
-  const hours = Math.floor((seconds % 86400) / 3600);
-  const mins = Math.floor((seconds % 3600) / 60);
-  if (days > 0) return `${days}d ${hours}h`;
-  if (hours > 0) return `${hours}h ${mins}m`;
-  return `${mins}m`;
-}
-
 function formatErrorRate(rate?: number): string {
   if (rate == null) return '\u2014';
   return `${(rate * 100).toFixed(1)}%`;
@@ -104,16 +84,6 @@ const LOG_LEVEL_ITEMS: ButtonGroupItem[] = [
   { value: 'trace', label: 'Trace', color: 'var(--text-muted)' },
 ];
 
-function mapLogLevel(level: string): LogEntry['level'] {
-  switch (level?.toUpperCase()) {
-    case 'ERROR': return 'error';
-    case 'WARN': case 'WARNING': return 'warn';
-    case 'DEBUG': return 'debug';
-    case 'TRACE': return 'trace';
-    default: return 'info';
-  }
-}
-
 // ── AgentHealth page ─────────────────────────────────────────────────────────
 
 export default function AgentHealth() {
@@ -195,35 +165,6 @@ export default function AgentHealth() {
 
   // Map events to FeedEvent
   const feedEvents: FeedEvent[] = useMemo(() => {
-    const eventIcon = (type: string) => {
-      switch (type) {
-        case 'REGISTERED': return <UserPlus size={14} />;
-        case 'DEREGISTERED': return <UserMinus size={14} />;
-        case 'AGENT_STARTED': return <Play size={14} />;
-        case 'AGENT_STOPPED': return <Square size={14} />;
-        case 'WENT_STALE': return <Clock size={14} />;
-        case 'WENT_DEAD': return <Skull size={14} />;
-        case 'RECOVERED': return <HeartPulse size={14} />;
-        case 'ROUTE_STATE_CHANGED': return <Route size={14} />;
-        case 'COMMAND_DELIVERED':
-        case 'COMMAND_ACKNOWLEDGED': return <Send size={14} />;
-        default: return <Activity size={14} />;
-      }
-    };
-
-    const eventSeverity = (type: string): FeedEvent['severity'] => {
-      switch (type) {
-        case 'WENT_DEAD':
-        case 'AGENT_STOPPED':
-        case 'DEREGISTERED': return 'error';
-        case 'WENT_STALE': return 'warning';
-        case 'RECOVERED':
-        case 'REGISTERED':
-        case 'AGENT_STARTED': return 'success';
-        default: return 'running';
-      }
-    };
-
     const mapped = (events ?? []).map((e: { id: number; instanceId: string; eventType: string; detail: string; timestamp: string }) => ({
       id: String(e.id),
       severity: eventSeverity(e.eventType),