feat(quiz): couples quiz with shareable watermarked results card

Replaces the notify-me quiz stub with a full loop: quiz sessions per
couple, answer-and-guess flow, dual-direction scoring, and a score-only
share card (no question or answer content) captured via ViewShot with
Sauci branding.

API: migration 0019 (quiz_questions, quiz_sessions, quiz_answers, 12
seeded questions), new quiz domain with session start / current /
answers / result routes, couple isolation, route + integration +
scoring unit tests.

Mobile: src/features/quiz feature (intro, per-question self+guess flow,
waiting-for-partner nudge, results with breakdown), quizStore with
sign-out clearing, QuizShareModal following SharePreviewModal, discovery
QuizTile, analytics events, and tests.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

apps/api/drizzle/0019_quiz.sql

@@ -0,0 +1,65 @@
+-- Couples quiz: a shareable "how well do you know each other?" loop. Each partner
+-- answers every question twice, once about themselves and once guessing their
+-- partner, and the session only scores once both partners have a complete set.
+CREATE TABLE IF NOT EXISTS "quiz_questions" (
+  "id" uuid PRIMARY KEY DEFAULT gen_random_uuid(),
+  "prompt_self" text NOT NULL UNIQUE,
+  "prompt_guess" text NOT NULL,
+  "options" text[] NOT NULL CHECK (array_length("options", 1) BETWEEN 2 AND 4),
+  "sort_order" integer NOT NULL DEFAULT 0,
+  "is_active" boolean NOT NULL DEFAULT true,
+  "created_at" timestamptz NOT NULL DEFAULT now()
+);
+--> statement-breakpoint
+CREATE TABLE IF NOT EXISTS "quiz_sessions" (
+  "id" uuid PRIMARY KEY DEFAULT gen_random_uuid(),
+  "couple_id" uuid NOT NULL REFERENCES "couples"("id") ON DELETE CASCADE,
+  "status" text NOT NULL DEFAULT 'active' CHECK ("status" IN ('active', 'completed')),
+  "question_ids" uuid[] NOT NULL,
+  "score_percent" integer,
+  "completed_at" timestamptz,
+  "created_at" timestamptz NOT NULL DEFAULT now()
+);
+--> statement-breakpoint
+CREATE UNIQUE INDEX IF NOT EXISTS "quiz_sessions_one_active_per_couple_idx"
+  ON "quiz_sessions" ("couple_id") WHERE "status" = 'active';
+--> statement-breakpoint
+CREATE INDEX IF NOT EXISTS "quiz_sessions_couple_id_created_at_idx"
+  ON "quiz_sessions" ("couple_id", "created_at" DESC);
+--> statement-breakpoint
+CREATE TABLE IF NOT EXISTS "quiz_answers" (
+  "session_id" uuid NOT NULL REFERENCES "quiz_sessions"("id") ON DELETE CASCADE,
+  "user_id" uuid NOT NULL,
+  "question_id" uuid NOT NULL,
+  "self_index" integer NOT NULL CHECK ("self_index" >= 0),
+  "guess_index" integer NOT NULL CHECK ("guess_index" >= 0),
+  "created_at" timestamptz NOT NULL DEFAULT now(),
+  PRIMARY KEY ("session_id", "user_id", "question_id")
+);
+--> statement-breakpoint
+INSERT INTO "quiz_questions" ("prompt_self", "prompt_guess", "options", "sort_order") VALUES
+  ('What is your idea of a perfect date night?', 'What is your partner''s idea of a perfect date night?',
+   ARRAY['Cosy night in', 'Fancy dinner out', 'Live music or a show', 'Something active or outdoorsy'], 10),
+  ('What comfort food do you crave the most?', 'What comfort food does your partner crave the most?',
+   ARRAY['Pizza', 'Ice cream', 'A home-cooked classic', 'Salty snacks'], 20),
+  ('How do you most like to receive love?', 'How does your partner most like to receive love?',
+   ARRAY['Words of affirmation', 'Quality time', 'Physical touch', 'Thoughtful gifts'], 30),
+  ('What is your biggest pet peeve at home?', 'What is your partner''s biggest pet peeve at home?',
+   ARRAY['Dishes left in the sink', 'Clothes on the floor', 'Being interrupted', 'Loud noises while resting'], 40),
+  ('If you could go anywhere on a dream holiday, where would it be?', 'If your partner could go anywhere on a dream holiday, where would it be?',
+   ARRAY['A beach escape', 'A big city adventure', 'A mountain retreat', 'A road trip somewhere new'], 50),
+  ('What movie genre do you reach for most?', 'What movie genre does your partner reach for most?',
+   ARRAY['Comedy', 'Romance', 'Action or thriller', 'Documentary'], 60),
+  ('Are you more of a morning person or a night person?', 'Is your partner more of a morning person or a night person?',
+   ARRAY['Morning person', 'Night person', 'A bit of both', 'Neither, honestly'], 70),
+  ('What hidden talent are you secretly proud of?', 'What hidden talent is your partner secretly proud of?',
+   ARRAY['Cooking or baking', 'Singing or dancing', 'A sport or game', 'Art or a craft'], 80),
+  ('What helps you relieve stress the most?', 'What helps your partner relieve stress the most?',
+   ARRAY['A quiet walk', 'Talking it out', 'Exercise', 'Watching something and switching off'], 90),
+  ('If you splurged on one thing, what would it be?', 'If your partner splurged on one thing, what would it be?',
+   ARRAY['New clothes', 'A gadget', 'A trip', 'A nice meal out'], 100),
+  ('What is your go-to karaoke song vibe?', 'What is your partner''s go-to karaoke song vibe?',
+   ARRAY['A power ballad', 'An upbeat pop anthem', 'An old classic', 'I would never do karaoke'], 110),
+  ('If you had one superpower, which would you pick?', 'If your partner had one superpower, which would they pick?',
+   ARRAY['Flight', 'Invisibility', 'Reading minds', 'Time travel'], 120)
+ON CONFLICT ("prompt_self") DO NOTHING;