Add Import/Export support (Anki, CSV)

[nicholaspsmith]

Summary

Enable users to import existing flashcards from other systems and export their data for backup or migration.

Motivation

• Users have existing study material in other apps
• Anki is the most popular flashcard app with large user base
• Data portability builds user trust
• Export enables backup and sharing

Import Formats

Anki (.apkg)

• SQLite-based format containing cards, decks, media
• Most common import request
• Preserve review history if possible

CSV/TSV

• Simple format: question,answer,tags
• Common for bulk import from spreadsheets
• Support custom column mapping

Markdown

• Q/A pairs in markdown format
• Natural for technical content

• ## Question
  What is a pod in Kubernetes?
  
  ## Answer
  The smallest deployable unit...
  

Export Formats

CSV

• Simple export: question, answer, tags, mastery%
• Review history optional

Anki (.apkg)

• Full compatibility with Anki desktop
• Include scheduling data

JSON

• Full data export for backup
• All metadata preserved

Technical Implementation

Anki Import

// Use sql.js to read SQLite in browser
import initSqlJs from 'sql.js'

async function parseAnkiPackage(file: File) {
  const SQL = await initSqlJs()
  const buffer = await file.arrayBuffer()
  const db = new SQL.Database(new Uint8Array(buffer))
  
  const cards = db.exec('SELECT id, flds FROM notes')
  // Parse fields and create flashcards
}

CSV Import

• Papa Parse for CSV parsing
• Column mapping UI
• Preview before import

Import Flow

1. Upload file
2. Parse and preview cards
3. Map to goal/skill tree node
4. Confirm import
5. Create flashcards in batches

UI Components

• Import wizard with step-by-step flow
• Format detection or selection
• Preview imported cards
• Progress indicator for large imports
• Export button in settings/goal pages

Acceptance Criteria

• Import Anki .apkg files
• Import CSV with column mapping
• Export to CSV format
• Export to Anki format
• Preview before importing
• Handle large files (1000+ cards)