Make note picker add notes to persistent context instead of one-shot

Previously the paperclip button created a one-shot attachment that was
only included for the single message it was sent with, then discarded.
Now selecting a note via the picker calls includeNote() directly, so it
appears in the "In Context" sidebar and stays for the entire conversation
— consistent with clicking "+" on a suggested note.

Removed attachedNote ref, removeAttachedNote(), the pinned-note sidebar
block, and the contextNoteId/contextNoteTitle sendMessage arguments that
are no longer needed.

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

frontend/src/views/ChatView.vue

@@ -27,7 +27,6 @@ const showResearchModal = ref(false);
 const researchTopic = ref("");
 
 // Note picker state
-const attachedNote = ref<{ id: number; title: string } | null>(null);
 const showNotePicker = ref(false);
 const noteSearchQuery = ref("");
 const noteSearchResults = ref<{ id: number; title: string }[]>([]);
@@ -99,7 +98,6 @@ watch(convId, async (newId) => {
   includedNoteIds.value = new Set();
   includedNotes.value = [];
   suggestedNotes.value = [];
-  attachedNote.value = null;
   store.lastContextMeta = null;
   if (newId) {
     // Skip re-fetch if this conversation is already loaded (avoids race
@@ -175,19 +173,15 @@ async function sendMessage() {
   }
 
   sending.value = true;
-  const contextNoteId = attachedNote.value?.id ?? undefined;
-  const contextNoteTitle = attachedNote.value?.title ?? undefined;
-  attachedNote.value = null;
   messageInput.value = "";
   resetTextareaHeight();
   scrollToBottom();
 
   await store.sendMessage(
     content,
-    contextNoteId,
+    undefined,
     includedNoteIds.value.size ? [...includedNoteIds.value] : undefined,
     true, // enable thinking in the full chat view
-    contextNoteTitle,
   );
   sending.value = false;
 
@@ -300,14 +294,10 @@ function onNoteSearchInput() {
 }
 
 function selectNote(note: { id: number; title: string }) {
-  attachedNote.value = note;
+  includeNote(note);
   showNotePicker.value = false;
 }
 
-function removeAttachedNote() {
-  attachedNote.value = null;
-}
-
 function includeNote(note: { id: number; title: string }) {
   if (includedNoteIds.value.has(note.id)) return;
   includedNoteIds.value = new Set([...includedNoteIds.value, note.id]);
@@ -471,20 +461,11 @@ onUnmounted(() => {
           </div>
 
           <!-- Context sidebar -->
-          <aside v-if="includedNotes.length || suggestedNotes.length || attachedNote" class="context-sidebar">
+          <aside v-if="includedNotes.length || suggestedNotes.length" class="context-sidebar">
             <!-- IN CONTEXT section -->
-            <template v-if="attachedNote || includedNotes.length">
+            <template v-if="includedNotes.length">
               <div class="context-sidebar-header">In Context</div>
 
-              <!-- Manually attached note — pinned until sent -->
-              <div v-if="attachedNote" class="context-note context-note-pinned">
-                <span class="context-note-icon" title="Attached for this message">📌</span>
-                <router-link :to="`/notes/${attachedNote.id}`" class="context-note-name">
-                  {{ attachedNote.title }}
-                </router-link>
-                <button class="context-note-remove" @click="removeAttachedNote" title="Remove">&times;</button>
-              </div>
-
               <!-- Explicitly included notes -->
               <div v-for="note in includedNotes" :key="note.id" class="context-note context-note-included">
                 <router-link :to="`/notes/${note.id}`" class="context-note-name">
@@ -805,13 +786,6 @@ onUnmounted(() => {
   border: 1px solid var(--color-border);
   font-size: 0.82rem;
 }
-.context-note-pinned {
-  border-color: var(--color-primary);
-}
-.context-note-icon {
-  font-size: 0.75rem;
-  flex-shrink: 0;
-}
 .context-note-name {
   flex: 1;
   min-width: 0;