feat(web): operator questions inline in chat, mascot reactions scoped to the focused task

The pending operator-question card now renders inline in ChatThread (the
newest thing in the conversation) instead of in the context rail — it's
part of the chat, not a separate side panel, and the panel's hasContext
gate no longer needs to special-case it.

The desktop mascot's reactions are now entirely about whichever task
window has focus, not fleet-wide events: thinking/talking is a new
continuous `busy` behavior that tracks the focused session's own
streaming state (thinking before any text arrives, talking once it
does — using the previously-unwired peep/talk sprite), eureka fires with
the actual knowledge title that was recorded, happy fires with the
task's own completion summary, and alarmed now means "this task needs
your OK" (an operator question was raised) rather than a fleet-wide
critical/signal event.

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

web/src/lib/components/OperatorQuestion.svelte

@@ -26,7 +26,7 @@
 
 {#if question}
   {@const q = question}
-  <div class="flex shrink-0 flex-col gap-2 border-b bg-warning/5 px-3 py-2.5">
+  <div class="flex flex-col gap-2 rounded-2xl border border-warning/30 bg-warning/5 px-3.5 py-3">
     <div class="flex items-start gap-2">
       <CircleHelpIcon class="mt-0.5 size-4 shrink-0 text-warning" />
       <div class="min-w-0 flex-1">