feat(telemetry): stamp service.name and network on native metrics

The native OTel metrics path hard-coded service.name="xrpld" and stamped
no network attribute, while traces stamped a configurable service.name
and xrpl.network.type. Metrics therefore could not be filtered by service
or network. Align the two paths:

- OTelCollector::New / OTelCollectorImp gain serviceName + networkType
  params. service.name uses the configured value (default "xrpld" when
  unset, preserving today's behavior); xrpl.network.type is stamped when
  provided. The key is a string literal because beast/insight sits below
  the telemetry module and cannot include its SpanNames const.
- CollectorManager reads service_name from [insight], falling back to the
  [telemetry] value, and receives the network type from the caller.
- Application derives the network type once via the shared
  telemetry::networkTypeFromId, now declared in Telemetry.h and moved out
  of an anonymous namespace so the trace and metric paths reuse a single
  0/1/2 -> mainnet/testnet/devnet mapping (no duplication).

Dashboards (5 system-* files): add $service_name, $deployment_environment,
$xrpl_network_type template variables and wire them into every panel query
that filters by $node.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/libxrpl/telemetry/TelemetryConfig.cpp

@@ -61,10 +61,10 @@ constexpr std::uint32_t batchDelayMs = 5000u;
 constexpr std::uint32_t maxQueueSize = 2048u;
 }  // namespace dflt
 
-/** Derive a human-readable network type label from the numeric network ID.
-    @param networkId  The network identifier from [network_id] config.
-    @return "mainnet", "testnet", "devnet", or "unknown" for other values.
-*/
+}  // namespace
+
+// Declared in Telemetry.h; shared by the trace and metric export paths so
+// both stamp the same xrpl.network.type resource attribute value.
 std::string
 networkTypeFromId(std::uint32_t networkId)
 {
@@ -81,8 +81,6 @@ networkTypeFromId(std::uint32_t networkId)
     }
 }
 
-}  // namespace
-
 Telemetry::Setup
 makeTelemetrySetup(
     Section const& section,