unified agent indicator at end of conversation

- New AgentIndicator component: replaces 3 separate indicators
  (loading dots, ToolCallGroup summary, activity bar) with one
- Positioned as last item in message list — scrolls naturally
- Shows current tool action: 'Researching lxc:nfs-export…' etc
- Spinner during work, check on completion, X on error
- Fades out 3s after turn completes
- Activity bar, loading dots, statusLabel removed from Chat
- Continue button moved to sidebar session panel

web/src/lib/components/AgentIndicator.svelte

@@ -0,0 +1,68 @@
+<script lang="ts">
+  import type { ToolCallResult } from '$lib/stores/chat'
+  import LoaderCircleIcon from '@lucide/svelte/icons/loader-circle'
+  import CheckIcon from '@lucide/svelte/icons/check'
+  import XIcon from '@lucide/svelte/icons/x'
+
+  let { active = false, lastTool = null as ToolCallResult | null, error = '' }: { active?: boolean; lastTool?: ToolCallResult | null; error?: string } = $props()
+
+  let done = $state(false)
+  let wasActive = $state(false)
+
+  $effect(() => {
+    if (active) { done = false; wasActive = true }
+    if (!active && wasActive) {
+      done = true
+      // Fade out after 3s
+      const t = setTimeout(() => { done = false; wasActive = false }, 3000)
+      return () => clearTimeout(t)
+    }
+  })
+
+  const label = $derived.by(() => {
+    if (error) return error
+    if (!active && done) return 'Done'
+    if (!lastTool) return 'Agent is thinking…'
+    const args = lastTool.args ?? {}
+    switch (lastTool.name) {
+      case 'set_goal': return 'Setting goal…'
+      case 'propose_plan': return 'Building plan…'
+      case 'search_knowledge': return `Researching: ${args.query ?? ''}`
+      case 'get_entity': return `Looking up ${args.slug_or_id ?? ''}`
+      case 'get_entity_knowledge': return `Checking prior knowledge…`
+      case 'get_relations': return `Checking relationships…`
+      case 'list_lxcs': return 'Listing containers…'
+      case 'list_entities': return 'Listing entities…'
+      case 'get_health_summary': return 'Checking fleet health…'
+      case 'run': {
+        const purpose = args.purpose ?? ''
+        const target = args.target ?? ''
+        if (purpose) return purpose
+        if (target) return `Running on ${target}…`
+        return 'Running command…'
+      }
+      case 'get_execution_status': return 'Checking execution status…'
+      case 'update_plan_step': return 'Updating progress…'
+      case 'upsert_knowledge': return 'Recording knowledge…'
+      case 'complete_task': return 'Wrapping up…'
+      case 'ping_service': return 'Checking service…'
+      case 'ask_operator': return 'Asking operator…'
+      default: return `${lastTool.name}…`
+    }
+  })
+</script>
+
+{#if active || done || error}
+  <div class="flex items-center gap-2 py-2 text-xs {error ? 'text-destructive' : done ? 'text-success' : 'text-muted-foreground'}" class:opacity-50={done} class:transition-opacity>
+    <span class="shrink-0">
+      {#if error}
+        <XIcon class="size-3" />
+      {:else if done}
+        <CheckIcon class="size-3" />
+      {:else}
+        <LoaderCircleIcon class="size-3 animate-spin text-primary" />
+      {/if}
+    </span>
+    <span>{label}</span>
+  </div>
+{/if}