Add RCON client + SendCurrency service (AtomCMS-faithful)

- rcon.ts: Node net.Socket transport speaking AtomCMS's exact protocol (raw
  JSON {"key","data"} over rcon_ip:rcon_port, fire-and-forget) with a bounded
  timeout + backoff retry; typed commands matching RconService EXACTLY
  (sendgift `itemid`, disconnect `username`, no-data => data:null, givepoints
  numeric `type`, forwarduser, setmotto/setrank/alertuser, give*). Injectable
  transport keeps command shapes unit-testable.
- send-currency.ts: mirrors the SendCurrency action — RCON deliver, else DB
  fallback (credits -> users.credits; duckets/diamonds/points -> users_currency
  by type 0/5/101).
- env: RCON_HOST/PORT/TIMEOUT/RETRIES. vitest: SKIP_ENV_VALIDATION for unit tests.

Verified: tsc exit 0, vitest 39/39, next build exit 0. Live TCP test deferred
(needs a running emulator).

src/lib/services/rcon.test.ts

@@ -0,0 +1,67 @@
+import { describe, expect, it } from "vitest";
+import { CurrencyType } from "./currency";
+import { RconClient, type RconPayload } from "./rcon";
+
+function spyClient() {
+  const sent: RconPayload[] = [];
+  const client = new RconClient(async (p) => {
+    sent.push(p);
+    return true;
+  });
+  return { client, sent };
+}
+
+describe("RconClient payloads (AtomCMS-faithful shapes)", () => {
+  it("givecredits", async () => {
+    const { client, sent } = spyClient();
+    await client.giveCredits(7, 100);
+    expect(sent[0]).toEqual({ key: "givecredits", data: { user_id: 7, credits: 100 } });
+  });
+
+  it("givepoints carries the numeric currency type", async () => {
+    const { client, sent } = spyClient();
+    await client.giveDiamonds(7, 3);
+    expect(sent[0]).toEqual({
+      key: "givepoints",
+      data: { user_id: 7, points: 3, type: CurrencyType.Diamonds },
+    });
+    expect(JSON.parse(JSON.stringify(sent[0])).data.type).toBe(5);
+  });
+
+  it("sendgift uses 'itemid' (not item_id)", async () => {
+    const { client, sent } = spyClient();
+    await client.sendGift(7, 42);
+    expect(sent[0]).toEqual({
+      key: "sendgift",
+      data: { user_id: 7, itemid: 42, message: "Here is a gift." },
+    });
+  });
+
+  it("disconnect carries username", async () => {
+    const { client, sent } = spyClient();
+    await client.disconnectUser(7, "alice");
+    expect(sent[0]).toEqual({ key: "disconnect", data: { user_id: 7, username: "alice" } });
+  });
+
+  it("no-data commands send data:null", async () => {
+    const { client, sent } = spyClient();
+    await client.updateWordFilter();
+    await client.updateCatalog();
+    expect(sent[0]).toEqual({ key: "updatewordfilter", data: null });
+    expect(sent[1]).toEqual({ key: "updatecatalog", data: null });
+  });
+
+  it("setmotto / setrank / forwarduser / alertuser shapes", async () => {
+    const { client, sent } = spyClient();
+    await client.setMotto(1, "hi");
+    await client.setRank(1, 7);
+    await client.forwardUser(1, 99);
+    await client.alertUser(1, "yo");
+    expect(sent).toEqual([
+      { key: "setmotto", data: { user_id: 1, motto: "hi" } },
+      { key: "setrank", data: { user_id: 1, rank: 7 } },
+      { key: "forwarduser", data: { user_id: 1, room_id: 99 } },
+      { key: "alertuser", data: { user_id: 1, message: "yo" } },
+    ]);
+  });
+});