Add note context visibility in chat and standardize UI design tokens

Improve chat context: build_context() now returns metadata about auto-found
notes, emitted as an SSE event so the frontend can display context pills
showing which notes influenced the response. Users can promote notes for
deeper context (+) or exclude irrelevant ones (x). A note picker lets users
manually attach notes. Multi-word search uses per-term AND matching, and
auto-search iterates keywords individually for broader OR-style coverage.

Standardize styling: introduce CSS design tokens (--radius-sm/md/lg/pill,
--color-success/warning/overlay, --focus-ring) and migrate all components
to use them. Fix header alignment to full-width, add active nav link state,
replace hardcoded colors with CSS variables, and normalize button padding.

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

frontend/src/stores/chat.ts

@@ -10,6 +10,7 @@ import {
 import type {
   Conversation,
   ConversationDetail,
+  ContextMeta,
   Message,
   OllamaModel,
   OllamaStatus,
@@ -22,6 +23,7 @@ export const useChatStore = defineStore("chat", () => {
   const loading = ref(false);
   const streaming = ref(false);
   const streamingContent = ref("");
+  const lastContextMeta = ref<ContextMeta | null>(null);
   const models = ref<OllamaModel[]>([]);
   const ollamaStatus = ref<"checking" | "available" | "unavailable">("checking");
   const modelStatus = ref<"checking" | "ready" | "not_found">("checking");
@@ -90,10 +92,15 @@ export const useChatStore = defineStore("chat", () => {
     }
   }
 
-  async function sendMessage(content: string, contextNoteId?: number | null) {
+  async function sendMessage(
+    content: string,
+    contextNoteId?: number | null,
+    excludeNoteIds?: number[],
+  ) {
     if (!currentConversation.value) return;
 
     const convId = currentConversation.value.id;
+    lastContextMeta.value = null;
 
     // Add optimistic user message
     const userMsg: Message = {
@@ -112,8 +119,15 @@ export const useChatStore = defineStore("chat", () => {
     try {
       await apiStreamPost(
         `/api/chat/conversations/${convId}/messages`,
-        { content, context_note_id: contextNoteId },
+        {
+          content,
+          context_note_id: contextNoteId,
+          exclude_note_ids: excludeNoteIds?.length ? excludeNoteIds : undefined,
+        },
         (data) => {
+          if (data.context) {
+            lastContextMeta.value = data.context as ContextMeta;
+          }
           if (data.chunk) {
             streamingContent.value += data.chunk as string;
           }
@@ -207,6 +221,7 @@ export const useChatStore = defineStore("chat", () => {
     loading,
     streaming,
     streamingContent,
+    lastContextMeta,
     models,
     ollamaStatus,
     modelStatus,