Restructure practice tests and clean up progress tracking

This commit restructures how practice test questions are stored by moving them from a JSONB column in the `practice_tests` table into a dedicated `practice_test_questions` table. This allows for better individual question querying and updating.

Key changes:
- Database migration to create the new `practice_test_questions` table and migrate existing JSONB data.
- Updated GraphQL schema:
    - `TermATP` snapshots now use `termSnapshot` and `defSnapshot`.
    - Added `id` to the `Question` type.
    - Replaced `updatePracticeTest` with `updatePracticeTestQuestion` to allow targeted FRQ updates.
    - Removed all references to the unused Leitner system and term progress history.
- Updated mutations and resolvers:
    - `RecordPracticeTest` now populates the new questions table.
    - `UpdatePracticeTestQuestion` implements manual FRQ correctness overrides and synchronizes practice test accuracy and term progress stats.
    - `PracticeTest.Questions` resolver now fetches and reconstructs questions from the database.
- Cleanup of obsolete dataloaders, mapping tables, and models.
- Updated integration tests to match the new schema and logic.

Author: google-labs-jules[bot]

db/migrations/202606290020_restructure_practice_test_questions.sql

@@ -0,0 +1,99 @@
+-- migrate:up
+
+CREATE TYPE public.question_type AS ENUM ('MCQ', 'TFQ', 'FRQ');
+
+CREATE TABLE public.practice_test_questions (
+    id uuid DEFAULT gen_random_uuid() NOT NULL PRIMARY KEY,
+    practice_test_id uuid NOT NULL REFERENCES public.practice_tests(id) ON DELETE CASCADE,
+    term_id uuid NOT NULL REFERENCES public.terms(id) ON DELETE CASCADE,
+    term_snapshot text NOT NULL,
+    def_snapshot text NOT NULL,
+    type public.question_type NOT NULL,
+    answer_with public.answer_with_enum NOT NULL,
+    correct boolean NOT NULL,
+    position integer NOT NULL,
+    data jsonb NOT NULL,
+    UNIQUE (practice_test_id, position)
+);
+
+-- Migrate data
+INSERT INTO public.practice_test_questions (
+    practice_test_id, term_id, term_snapshot, def_snapshot, type, answer_with, correct, position, data
+)
+SELECT
+    pt.id,
+    (q->COALESCE(sub.type_lower, 'mcq')->'term'->>'id')::uuid,
+    q->COALESCE(sub.type_lower, 'mcq')->'term'->>'term',
+    q->COALESCE(sub.type_lower, 'mcq')->'term'->>'def',
+    sub.type_upper,
+    (q->COALESCE(sub.type_lower, 'mcq')->>'answerWith')::public.answer_with_enum,
+    CASE
+        WHEN sub.type_upper = 'FRQ' THEN
+            COALESCE((q->'frq'->>'correct')::boolean, false) OR COALESCE((q->'frq'->>'userMarkedCorrect')::boolean, false)
+        ELSE
+            COALESCE((q->sub.type_lower->>'correct')::boolean, false)
+    END,
+    pos::int - 1,
+    CASE
+        WHEN sub.type_upper = 'MCQ' THEN
+            jsonb_build_object(
+                'distractors', (
+                    SELECT jsonb_agg(
+                        jsonb_build_object(
+                            'id', d->>'id',
+                            'termSnapshot', d->>'term',
+                            'defSnapshot', d->>'def'
+                        )
+                    )
+                    FROM jsonb_array_elements(q->'mcq'->'distractors') d
+                ),
+                'correctChoiceIndex', (q->'mcq'->>'correctChoiceIndex')::int,
+                'answeredIndex', (q->'mcq'->>'answeredIndex')::int
+            )
+        WHEN sub.type_upper = 'TFQ' THEN
+            jsonb_build_object(
+                'answeredBool', (q->'tfq'->>'answeredBool')::boolean,
+                'distractor', CASE
+                    WHEN q->'tfq'->'distractor' IS NOT NULL AND q->'tfq'->'distractor' != 'null'::jsonb THEN
+                        jsonb_build_object(
+                            'id', q->'tfq'->'distractor'->>'id',
+                            'termSnapshot', q->'tfq'->'distractor'->>'term',
+                            'defSnapshot', q->'tfq'->'distractor'->>'def'
+                        )
+                    ELSE NULL
+                END
+            )
+        WHEN sub.type_upper = 'FRQ' THEN
+            jsonb_build_object(
+                'answeredString', q->'frq'->>'answeredString',
+                'userMarkedCorrect', COALESCE((q->'frq'->>'userMarkedCorrect')::boolean, false)
+            )
+    END
+FROM public.practice_tests pt
+CROSS JOIN LATERAL jsonb_array_elements(pt.questions) WITH ORDINALITY AS q_arr(q, pos)
+CROSS JOIN LATERAL (
+    SELECT
+        CASE
+            WHEN q ? 'mcq' THEN 'mcq'
+            WHEN q ? 'tfq' THEN 'tfq'
+            WHEN q ? 'frq' THEN 'frq'
+        END as type_lower,
+        CASE
+            WHEN q ? 'mcq' THEN 'MCQ'::public.question_type
+            WHEN q ? 'tfq' THEN 'TFQ'::public.question_type
+            WHEN q ? 'frq' THEN 'FRQ'::public.question_type
+        END as type_upper
+) sub;
+
+ALTER TABLE public.practice_tests DROP COLUMN questions;
+DROP TABLE IF EXISTS public.practice_test_question_terms;
+DROP TABLE IF EXISTS public.practice_test_distractor_terms;
+DROP TABLE IF EXISTS public.term_progress_history;
+ALTER TABLE public.term_progress DROP COLUMN IF EXISTS term_leitner_system_box;
+ALTER TABLE public.term_progress DROP COLUMN IF EXISTS def_leitner_system_box;
+
+GRANT SELECT, INSERT, UPDATE, DELETE ON public.practice_test_questions TO quizfreely_api;
+
+-- migrate:down
+DROP TABLE public.practice_test_questions;
+DROP TYPE public.question_type;