Replace RCON with API-only emulator transport

- Switch default EMULATOR_MODE from 'rcon' to 'api'
- Remove RCON_HOST/PORT/timeout/maxRetries env vars
- Add EMULATOR_API_URL to .env and .env.example
- Update createEmulatorTransport() to use HTTP API only
- Remove rconHost/port from offline alert context
- All 827 tests pass, TypeScript compiles cleanly

src/env.ts

@@ -40,17 +40,11 @@ const schema = z
 		SMTP_USER: z.string().optional(),
 		SMTP_PASSWORD: z.string().optional(),
 		SMTP_FROM: z.string().optional(),
-		// RCON link to the Arcturus emulator (raw-JSON TCP protocol).
-		RCON_HOST: z.string().default("127.0.0.1"),
-		RCON_PORT: z.coerce.number().int().positive().default(3001),
-		RCON_TIMEOUT_MS: z.coerce.number().int().positive().default(10_000),
-		RCON_MAX_RETRIES: z.coerce.number().int().positive().default(3),
-		// Emulator transport selection. "rcon" uses the raw-JSON TCP protocol
-		// above; "api" uses an HTTP endpoint that accepts the same
+		// Emulator transport selection. "api" uses an HTTP endpoint that accepts the same
 		// `{"key":...,"data":...}` payload (for emulators without RCON).
-		EMULATOR_MODE: z.enum(["rcon", "api"]).default("rcon"),
+		EMULATOR_MODE: z.enum(["rcon", "api"]).default("api"),
 		// HTTP endpoint used when EMULATOR_MODE=api. Required in that mode.
-		EMULATOR_API_URL: z.string().url().optional(),
+		EMULATOR_API_URL: z.string().url(),
 		// Optional bearer/key auth for the API transport. When set, it is sent
 		// as `${EMULATOR_API_KEY_HEADER}: ${EMULATOR_API_KEY}` (default header
 		// "Authorization").