Add shared notes with tabbed pages editable by user and AI

Adds a note_pages table backing a tabbed notes panel where the user and
the model can both read and write. Only page titles (plus a short
preview) are injected into the system prompt on every turn; full page
content is kept out of context and fetched on demand via a read_note
tool, with write_note letting the model append to, replace, or create a
page.

Generalizes llm.resolve_web_search into resolve_tool_calls so the
tool-calling loop handles web_search and the new note tools through one
path. The chat stream emits a notes_updated SSE event when the model
edits a note so the frontend panel can refresh; local edits are tracked
as dirty and never clobbered by that refresh.

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

frontend/src/stores/chat.ts

@@ -1,4 +1,5 @@
 import { defineStore } from 'pinia'
+import { useNotesStore } from './notes'
 import { ref, computed } from 'vue'
 import { fetchSessions, fetchMessages, deleteSession, exportSession, importSession, streamChat, type SessionInfo, type Source, type ImportPayload } from '../api/client'
 
@@ -115,6 +116,9 @@ export const useChatStore = defineStore('chat', () => {
           messages.value[msgIdx].content += chunk.value as string
         } else if (chunk.type === 'sources' && chunk.value) {
           messages.value[msgIdx].sources = chunk.value as Source[]
+        } else if (chunk.type === 'notes_updated') {
+          // AIが共有ノートを書き換えたので、開いているノートパネルに反映する
+          useNotesStore().load().catch((e) => pushToast(`ノート更新失敗: ${e.message}`))
         } else if (chunk.type === 'done') {
           messages.value[msgIdx].pending = false
           isStreaming.value = false