fix: chat evaluation bugs — task pipeline, prompt grounding, markdown rendering

Addresses 14 bugs from 3 rounds of deep chat evaluation:

- Add chat-to-task pipeline in agents.py with regex-based intent detection,
  agent extraction, priority extraction, and title cleaning
- Filter meta-questions ("how do I create a task?") from task creation
- Inject real-time date/time context into every chat message
- Inject live queue state when user asks about tasks
- Ground system prompts with agent roster, honesty guardrails, self-knowledge,
  math delegation template, anti-filler rules, values-conflict guidance
- Add CSS for markdown code blocks, inline code, lists, blockquotes in chat
- Add highlight.js CDN for syntax highlighting in chat responses
- Reduce small-model memory context budget (4000→2000) for expanded prompt
- Add 27 comprehensive tests covering the full chat-to-task pipeline

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/dashboard/templates/partials/chat_message.html

@@ -12,6 +12,9 @@
     var el = document.currentScript.previousElementSibling.querySelector('.timmy-md');
     if (el && typeof marked !== 'undefined' && typeof DOMPurify !== 'undefined') {
       el.innerHTML = DOMPurify.sanitize(marked.parse(el.textContent));
+      if (typeof hljs !== 'undefined') {
+        el.querySelectorAll('pre code').forEach(function(block) { hljs.highlightElement(block); });
+      }
     }
   })();
 </script>