feat: MVP-5 P2 - Export/Import, Settings, Tests y Validaciones

- Ticket 10: Navegación completa de listas por teclado (↑↓ Enter E F P)
- Ticket 13: Historial de navegación contextual con recent-context-list
- Ticket 17: Exportación mejorada a Markdown con frontmatter
- Ticket 18: Exportación HTML simple y legible
- Ticket 19: Importador Markdown mejorado con frontmatter, tags, wiki links
- Ticket 20: Importador Obsidian-compatible (wiki links, #tags inline)
- Ticket 21: Centro de respaldo y portabilidad en Settings
- Ticket 22: Configuración visible de feature flags
- Ticket 24: Tests de command palette y captura externa
- Ticket 25: Harden de validaciones y límites (50MB backup, 10K notas, etc)

src/app/api/export-import/route.ts

@@ -4,6 +4,8 @@ import { noteSchema, NoteInput } from '@/lib/validators'
 import { createErrorResponse, createSuccessResponse, ValidationError } from '@/lib/errors'
 import { syncBacklinks } from '@/lib/backlinks'
 import { createBackupSnapshot } from '@/lib/backup'
+import { notesToMarkdownZip, noteToMarkdown } from '@/lib/export-markdown'
+import { notesToHtmlZip, noteToHtml } from '@/lib/export-html'
 
 export async function GET(req: NextRequest) {
   try {
@@ -26,6 +28,38 @@ export async function GET(req: NextRequest) {
       updatedAt: note.updatedAt.toISOString(),
     }))
 
+    if (format === 'markdown') {
+      const notesForExport = notes.map(note => ({
+        ...note,
+        tags: note.tags,
+        createdAt: note.createdAt.toISOString(),
+        updatedAt: note.updatedAt.toISOString(),
+      }))
+      if (notes.length === 1) {
+        return createSuccessResponse({
+          filename: notesToMarkdownZip(notesForExport).files[0].name,
+          content: noteToMarkdown(notesForExport[0]),
+        })
+      }
+      return createSuccessResponse(notesToMarkdownZip(notesForExport))
+    }
+
+    if (format === 'html') {
+      const notesForExport = notes.map(note => ({
+        ...note,
+        tags: note.tags,
+        createdAt: note.createdAt.toISOString(),
+        updatedAt: note.updatedAt.toISOString(),
+      }))
+      if (notes.length === 1) {
+        return createSuccessResponse({
+          filename: notesToHtmlZip(notesForExport).files[0].name,
+          content: noteToHtml(notesForExport[0]),
+        })
+      }
+      return createSuccessResponse(notesToHtmlZip(notesForExport))
+    }
+
     return createSuccessResponse(exportData)
   } catch (error) {
     return createErrorResponse(error)