feat(referrals): rework reward engine + email-verified landing

Reward engine:
- Recurring milestones (every 3 → +7d, every 5 → +14d) instead of one-time
  tiers capped at 5; idempotent + transactional grants serialised per
  referrer so concurrent qualifications can't double-count.
- Rewards now gated on the referred user's email verification
  (afterEmailVerification hook); already-verified referees (OAuth) qualify
  at apply time.
- Reward days banked as users.referral_credit_days when the referrer has no
  live subscription, consumed on next trial start / activation (no more
  silently lost rewards).
- Accurate cumulative rewardDays in stats; getMyReferrals returns referee
  name/masked email/status.

Hardening / cleanup:
- onConflictDoNothing makes apply idempotent (no unhandled unique violation).
- Anti-fraud: normalizeEmail blocks self-referral via gmail dot/+tag aliases.
- Collision-safe referral code generation at signup.
- Single apply path (welcome onboarding modal); removed duplicate calls in
  register + subscription pages. Input validation on the apply code.

Email verification UX:
- Verification link now lands on a dedicated /email-verified confirmation
  page instead of the deep-linked VIN/search page.

Schema: referrals.status + qualified_at, users.referral_credit_days (0009).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

apps/api/drizzle/0009_referral_rewards_rework.sql

@@ -0,0 +1,3 @@
+ALTER TABLE "referrals" ADD COLUMN "status" varchar(20) DEFAULT 'pending' NOT NULL;--> statement-breakpoint
+ALTER TABLE "referrals" ADD COLUMN "qualified_at" timestamp with time zone;--> statement-breakpoint
+ALTER TABLE "users" ADD COLUMN "referral_credit_days" integer DEFAULT 0 NOT NULL;

apps/api/drizzle/meta/_journal.json

@@ -64,6 +64,13 @@
       "when": 1779633572753,
       "tag": "0008_common_sumo",
       "breakpoints": true
+    },
+    {
+      "idx": 9,
+      "version": "7",
+      "when": 1779703007129,
+      "tag": "0009_referral_rewards_rework",
+      "breakpoints": true
     }
   ]
 }