fix: minichat markdown rendering and weather temperature unit preference

- KnowledgeView minichat: render assistant messages through renderMarkdown
  so headers, bold, lists etc. display correctly instead of raw markdown
- get_weather tool: read user's temp_unit from briefing_config and convert
  temperatures to °F when preferred; also include temp_unit in the
  returned payload so the model can label values correctly

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

frontend/src/views/KnowledgeView.vue

@@ -3,6 +3,7 @@ import { ref, computed, watch, onMounted, onUnmounted, nextTick } from "vue";
 import { useRouter } from "vue-router";
 import { apiGet, apiPatch, transcribeAudio } from "@/api/client";
 import { fmtCompact } from "@/utils/dateFormat";
+import { renderMarkdown } from "@/utils/markdown";
 import { useChatStore } from "@/stores/chat";
 import { useSettingsStore } from "@/stores/settings";
 import { useVoiceRecorder } from "@/composables/useVoiceRecorder";
@@ -544,7 +545,7 @@ onUnmounted(() => {
           class="minichat-msg"
           :class="msg.role === 'user' ? 'msg--user' : 'msg--assistant'"
         >
-          <div class="msg-content" v-html="msg.role === 'assistant' ? msg.content : msg.content"></div>
+          <div class="msg-content" v-html="msg.role === 'assistant' ? renderMarkdown(msg.content) : msg.content"></div>
         </div>
         <div v-if="chatStore.streaming" class="minichat-msg msg--assistant">
           <div class="msg-content streaming-indicator">