feat(web): redesign task rail — Plan/Event log polish, entity graph resize fix

- Plan/Activity panels: humanize step titles, richer icons, empty states
  matching Scope's illustration style, pretty-printed expandable detail
- Activity log renamed to Event log; every step now expandable
- Chat: middle-truncate header title, remove redundant task-list rail and
  header stat cluster (duplicated in the sidebar), simplify markdown styling
- Fix --font-mono actually being a monospace font (was aliased to DM Sans)
- Replace rotating loader-circle spinner with a smoother fading-blade Spinner
- SessionGraph entity detail panel: resizable and self-clamping against its
  live container size (was overflowing into sibling sections), close button
- Dev launch config: fetch bearer token from the running api container so
  `npm run dev` works against the local compose stack without a hardcoded
  secret in a tracked file

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

web/src/lib/components/AgentIndicator.svelte

@@ -1,6 +1,6 @@
 <script lang="ts">
   import type { ActivityEntry } from '$lib/stores/activity'
-  import LoaderCircleIcon from '@lucide/svelte/icons/loader-circle'
+  import Spinner from './Spinner.svelte'
   import CheckIcon from '@lucide/svelte/icons/check'
   import XIcon from '@lucide/svelte/icons/x'
 
@@ -34,7 +34,7 @@
       {:else if done}
         <CheckIcon class="size-3" />
       {:else}
-        <LoaderCircleIcon class="size-3 animate-spin text-primary" />
+        <Spinner class="size-3 text-primary" />
       {/if}
     </span>
     <span>{label}</span>