pvp: make the blood token ledger server-authoritative

The PvP_Characters table tallied wins and losses but held no token
balance and no purchase endpoint: earnings were client-reported
(winners credited themselves locally), so verifying only a spend
would have been security theater — a cheater could mint tokens by
self-reporting battle wins.

The server is now the ledger authority (FRE-142): registerCharacter
seeds the balance from the client cache exactly once and reconciles
it on every sync; battleResult requires the verified Lineage JWT
bearer, rejects non-participants, and credits the winner via the
reward formula ported from the client (computed from both registered
rows); a new purchase mutation checks cost, balance, and cooldown in
one conditional UPDATE scoped to the caller-owned row, so the spend
is atomic under concurrency and rate limiting survives cold starts.
Schema changes ship as an idempotent pvp-schema bootstrap
(pvpTokens, ownerUserId, lastPurchaseAt), mirroring the
analytics-schema pattern.

Client-side counterpart shipped in the lineage repo; design record
in its docs/security/pvp-server-side-purchases.md.

Tests: pvp-schema (DDL + legacy-column migration + idempotency),
pvp-rewards (formula parity with the client port, cost table),
pvp-ledger (seed-once reconciliation, owner binding, participant
verification, atomic spend, cooldown, refusal reasons) — 31 new tests
against in-memory SQLite; suite 572 pass (1 pre-existing audit
date-filter failure, unrelated).

src/routes/api/lineage/pvp/purchase.ts

@@ -0,0 +1,8 @@
+import type { APIEvent } from "@solidjs/start/server";
+import { rest } from "../_lib";
+
+// POST /api/lineage/pvp/purchase — server-authoritative Blood Token purchase
+export const POST = (event: APIEvent) => rest(async (caller) => {
+  const input = await event.request.json();
+  return caller.lineage.pvp.purchase(input);
+}, event);