feat(web): fold Events/Agent/Audit into EntityDetail; tag agent_activity with entity_id

Events, Agent, and Audit were standalone read-only pages that never
cross-referenced the entity they related to. Fold them into EntityDetail
as entity-scoped cards (Agent activity, Audit trail) alongside the
existing Signals/Executions/Knowledge cards, and give the Signals card
real Ack/Mute/Resolve actions. Signals stays a standalone page since
it's the only one with cross-entity triage value (badge count, actions).

Also fixes the underlying reason those new cards would've stayed empty:
agent_activity rows were never tagged with entity_id at insert time
(cmd/nomos/store.go, internal/mcp/server.go), even though the column
and the API filter both support it. Added a best-effort resolver that
checks common tool-arg keys (target, entity_slug, slug, ...) against
the entities table.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

web/src/App.svelte

@@ -3,15 +3,12 @@
   import Tasks from './pages/Tasks.svelte'
   import Overview from './pages/Overview.svelte'
   import Entities from './pages/Entities.svelte'
-  import Events from './pages/Events.svelte'
   import Ops from './pages/Ops.svelte'
   import Signals from './pages/Signals.svelte'
   import Graph from './pages/Graph.svelte'
   import EntityDetail from './pages/EntityDetail.svelte'
-  import Agent from './pages/Agent.svelte'
   import Knowledge from './pages/Knowledge.svelte'
   import Learning from './pages/Learning.svelte'
-  import Audit from './pages/Audit.svelte'
   import { newChat } from '$lib/stores/chat'
   import { summary, subscribeContext, openSignalCount } from '$lib/stores/context'
   import { connectionState } from '$lib/stores/events'
@@ -27,14 +24,11 @@
   import MessageSquareIcon from '@lucide/svelte/icons/message-square'
   import LayoutDashboardIcon from '@lucide/svelte/icons/layout-dashboard'
   import DatabaseIcon from '@lucide/svelte/icons/database'
-  import ActivityIcon from '@lucide/svelte/icons/activity'
   import PanelRightIcon from '@lucide/svelte/icons/panel-right'
   import ShieldCheckIcon from '@lucide/svelte/icons/shield-check'
   import SirenIcon from '@lucide/svelte/icons/siren'
   import NetworkIcon from '@lucide/svelte/icons/share-2'
-  import BotIcon from '@lucide/svelte/icons/bot'
   import SearchIcon from '@lucide/svelte/icons/search'
-  import ScrollTextIcon from '@lucide/svelte/icons/scroll-text'
   import TrendingUpIcon from '@lucide/svelte/icons/trending-up'
 
   let page = $state('tasks')
@@ -71,11 +65,8 @@
     { id: 'graph', label: 'Graph', icon: NetworkIcon },
     { id: 'ops', label: 'Operations', icon: ShieldCheckIcon, badge: () => approvalsPending },
     { id: 'signals', label: 'Signals', icon: SirenIcon, badge: () => openSignals },
-    { id: 'events', label: 'Events', icon: ActivityIcon },
-    { id: 'agent', label: 'Agent', icon: BotIcon },
     { id: 'knowledge', label: 'Knowledge', icon: SearchIcon },
-    { id: 'learning', label: 'Learning', icon: TrendingUpIcon },
-    { id: 'audit', label: 'Audit', icon: ScrollTextIcon }
+    { id: 'learning', label: 'Learning', icon: TrendingUpIcon }
   ]
 </script>
 
@@ -220,16 +211,10 @@
         <Ops />
       {:else if page === 'signals'}
         <Signals />
-      {:else if page === 'events'}
-        <Events />
-      {:else if page === 'agent'}
-        <Agent />
       {:else if page === 'knowledge'}
         <Knowledge />
       {:else if page === 'learning'}
         <Learning />
-      {:else if page === 'audit'}
-        <Audit />
       {:else}
         <Chat />
       {/if}