Phase 11: FUT Champions mode and Division Rivals weekly rewards

FUT Champions (Weekend League):
- POST /fut-champs/start — open a new 30-match week (one active session at a time)
- GET /fut-champs — current session status with matches_remaining
- POST /fut-champs/:id/result — record a match; auto-completes and computes tier at 30
- POST /fut-champs/:id/claim — claim coins + pack reward (idempotent guard)
- GET /fut-champs/history — past sessions newest-first
- 11 reward tiers: Elite (27+ wins, 50k coins + icon pack) down to Bronze 1 (0 wins, 250 coins)

Division Rivals:
- POST /rivals/claim-weekly — claim weekly reward scaled by current division
- Week counter is monotonic (offline-safe, no real-time calendar dependency)
- Division 1-3 get a bonus pack alongside coins

Migration 0008 adds fut_champs_sessions table and two columns to seasons.
12 new integration tests — all 67 pass, clippy clean.

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

migrations/0008_fut_champs.sql

@@ -0,0 +1,21 @@
+-- Phase 11: FUT Champions / Weekend League sessions
+CREATE TABLE IF NOT EXISTS fut_champs_sessions (
+    id TEXT PRIMARY KEY,
+    profile_id TEXT NOT NULL,
+    week_number INTEGER NOT NULL DEFAULT 1,
+    matches_played INTEGER NOT NULL DEFAULT 0,
+    wins INTEGER NOT NULL DEFAULT 0,
+    draws INTEGER NOT NULL DEFAULT 0,
+    losses INTEGER NOT NULL DEFAULT 0,
+    status TEXT NOT NULL DEFAULT 'active',
+    reward_tier TEXT,
+    reward_coins INTEGER,
+    reward_pack_id TEXT,
+    reward_claimed INTEGER NOT NULL DEFAULT 0,
+    started_at TEXT NOT NULL,
+    completed_at TEXT
+);
+
+-- Division Rivals: track when each profile last claimed their weekly reward
+ALTER TABLE seasons ADD COLUMN rivals_week_claimed INTEGER NOT NULL DEFAULT 0;
+ALTER TABLE seasons ADD COLUMN rivals_total_points INTEGER NOT NULL DEFAULT 0;