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/app.css

@@ -4,7 +4,7 @@
 
 @theme inline {
   --font-sans: 'DM Sans', system-ui, sans-serif;
-  --font-mono: 'DM Sans', system-ui, sans-serif;
+  --font-mono: 'DM Mono', ui-monospace, 'SF Mono', Menlo, Consolas, monospace;
   --font-heading: 'Inknut Antiqua', Georgia, serif;
   --radius-sm: calc(var(--radius) - 4px);
   --radius-md: calc(var(--radius) - 2px);