plan-approve-once policy + cooler empty states + remove graph header

Backend:
- proposePlan sets plan window in autonomy_settings (nomos:plan:<session>)
- run handler checks plan window — auto-executes config_mutation commands
  within plan without per-action approval
- planWindowActive function in server.go
- Plan window cleaned up on completeTask (already covered by LIKE '%:' || )

Frontend:
- Removed 'Session graph' header bar
- Cooler empty states: Plan shows animated dots + 'Awaiting plan…',
  Activity shows pulsing dots + 'Waiting for activity…'

web/src/lib/components/ActivityTimeline.svelte

@@ -43,8 +43,13 @@
 <div class="flex h-full flex-col">
   <div class="flex-1 overflow-y-auto">
     {#if $activityLog.length === 0}
-      <div class="px-3 py-6 text-center text-xs text-muted-foreground">
-        Waiting for agent activity…
+      <div class="flex flex-col items-center gap-2 px-3 py-6 text-center">
+        <div class="flex items-center gap-0.5">
+          <div class="size-1 rounded-full bg-muted-foreground/20 animate-pulse" style="animation-delay:0s" />
+          <div class="size-1 rounded-full bg-muted-foreground/30 animate-pulse" style="animation-delay:0.15s" />
+          <div class="size-1 rounded-full bg-muted-foreground/20 animate-pulse" style="animation-delay:0.3s" />
+        </div>
+        <p class="text-xs text-muted-foreground">Waiting for activity…</p>
       </div>
     {:else}
       <div class="flex flex-col py-1">

web/src/lib/components/SessionGraph.svelte

@@ -300,12 +300,6 @@
 </script>
 
 <aside class="flex h-full min-h-0 flex-col bg-card/40">
-  <div class="flex shrink-0 items-center justify-between border-b px-3 py-2">
-    <p class="text-[11px] font-semibold uppercase tracking-wider text-muted-foreground">Session graph</p>
-    {#if nodes.length}
-      <span class="text-[11px] text-muted-foreground">{nodes.length} {nodes.length === 1 ? 'entity' : 'entities'}</span>
-    {/if}
-  </div>
   {#if nowTouching}
     <div class="flex shrink-0 items-center gap-1.5 border-b bg-primary/5 px-3 py-1.5 text-[11px] text-primary">
       <span class="size-1.5 animate-pulse rounded-full bg-primary"></span>

web/src/lib/components/TaskContextPanel.svelte

@@ -144,8 +144,13 @@
             {/each}
           </ol>
         {:else}
-          <div class="px-3 py-3 text-center text-xs text-muted-foreground">
-            No plan yet
+          <div class="flex flex-col items-center gap-2 px-3 py-6 text-center">
+            <div class="flex gap-1">
+              <div class="size-1.5 rounded-full bg-muted-foreground/20" />
+              <div class="size-1.5 rounded-full bg-muted-foreground/30" />
+              <div class="size-1.5 rounded-full bg-muted-foreground/20" />
+            </div>
+            <p class="text-xs text-muted-foreground">Awaiting plan…</p>
           </div>
         {/if}
       </div>