Phase 4: upload, LLM extraction, import review flow

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

internal/db/schema.sql

@@ -54,6 +54,14 @@ CREATE TABLE IF NOT EXISTS sessions (
 );
 CREATE INDEX IF NOT EXISTS idx_sessions_expiry ON sessions(expiry);
 
+CREATE TABLE IF NOT EXISTS import_drafts (
+  id TEXT PRIMARY KEY,
+  user_id INTEGER NOT NULL REFERENCES users(id),
+  source TEXT NOT NULL DEFAULT '',
+  questions TEXT NOT NULL,
+  created_at DATETIME DEFAULT CURRENT_TIMESTAMP
+);
+
 CREATE INDEX IF NOT EXISTS idx_test_answers_test ON test_answers(test_id);
 CREATE INDEX IF NOT EXISTS idx_answers_question ON answers(question_id);
 CREATE INDEX IF NOT EXISTS idx_stats_user ON user_question_stats(user_id);