feat(ux): epic UX design improvements across agents, chat, notes, and i18n

Comprehensive UI/UX updates including agent card redesign, chat container
improvements, note editor enhancements, memory echo notifications, and
updated translations for all 15 locales.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

keep-notes/lib/ai/tools/note-search.tool.ts

@@ -14,12 +14,13 @@ toolRegistry.register({
   isInternal: true,
   buildTool: (ctx) =>
     tool({
-      description: 'Search the user\'s notes by keyword or semantic meaning. Returns matching notes with titles and content excerpts.',
+      description: 'Search the user\'s notes by keyword or semantic meaning. Returns matching notes with titles and content excerpts. Optionally restrict to a specific notebook.',
       inputSchema: z.object({
         query: z.string().describe('The search query'),
         limit: z.number().optional().describe('Max results to return (default 5)').default(5),
+        notebookId: z.string().optional().describe('Optional notebook ID to restrict search to a specific notebook'),
       }),
-      execute: async ({ query, limit = 5 }) => {
+      execute: async ({ query, limit = 5, notebookId }) => {
         try {
           // Keyword fallback search using Prisma
           const keywords = query.toLowerCase().split(/\s+/).filter(w => w.length > 2)
@@ -31,6 +32,7 @@ toolRegistry.register({
           const notes = await prisma.note.findMany({
             where: {
               userId: ctx.userId,
+              ...(notebookId ? { notebookId } : {}),
               ...(conditions.length > 0 ? { OR: conditions } : {}),
               isArchived: false,
               trashedAt: null,