feat(telemetry): initial implementation — OpenTelemetry traces, metrics, logs (v1.0.0)

Introduces code.nochebuena.dev/einherjar/telemetry — the observability bootstrap
starter for the Einherjar framework. Absorbs the telemetry package from micro-lib,
migrating from OpenCensus to OpenTelemetry SDK v1.42.

Bootstrap functions (not lifecycle.Component — telemetry must be initialized before
the launcher starts, and its shutdown must run after all components stop):
- New(ctx, cfg) (func(context.Context) error, error) — production mode; exports
  traces, metrics, and logs via OTLP over gRPC to the configured endpoint;
  returns a shutdown function to be deferred in main()
- NewConsole(ctx, logger, cfg) (func(context.Context) error, error) — development
  mode; writes structured telemetry to the provided logging.Logger; no network
  dependency; suitable for local development and CI

Config (EINHERJAR_OTEL_* env vars):
  ServiceName(required), ServiceVersion(unknown), Environment(development),
  OTLPEndpoint(required for New), OTLPInsecure(false)

ConsoleConfig (EINHERJAR_OTEL_* env vars):
  ServiceName(required), ServiceVersion(unknown), Environment(development)

- identifiable.go: package-level Module variable (observability.Identifiable) for version
  identification — telemetry bootstraps before the launcher; not registered as a lifecycle component

config.go

@@ -0,0 +1,25 @@
+package telemetry
+
+// Config holds OTel bootstrap configuration.
+type Config struct {
+	// ServiceName identifies the service in traces, metrics, and logs.
+	ServiceName string `env:"EINHERJAR_OTEL_SERVICE_NAME,required"`
+	// ServiceVersion is the deployed version (e.g. "1.4.2").
+	ServiceVersion string `env:"EINHERJAR_OTEL_SERVICE_VERSION" envDefault:"unknown"`
+	// Environment is the deployment environment (e.g. "production", "staging").
+	Environment string `env:"EINHERJAR_OTEL_ENVIRONMENT" envDefault:"development"`
+	// OTLPEndpoint is the OTLP gRPC collector address (e.g. "alloy:4317").
+	OTLPEndpoint string `env:"EINHERJAR_OTEL_EXPORTER_ENDPOINT,required"`
+	// OTLPInsecure disables TLS for the OTLP connection. Set true in development.
+	OTLPInsecure bool `env:"EINHERJAR_OTEL_EXPORTER_INSECURE" envDefault:"false"`
+}
+
+// DefaultConfig returns a Config with optional fields set to production-safe defaults.
+// Callers must supply ServiceName and OTLPEndpoint.
+func DefaultConfig() Config {
+	return Config{
+		ServiceVersion: "unknown",
+		Environment:    "development",
+		OTLPInsecure:   false,
+	}
+}