feat(telemetry): initial stable release v0.9.0

Single-call OTel SDK bootstrap setting all three global providers (traces → Tempo, metrics → Mimir, logs → Loki) over OTLP gRPC.

What's included:
- New(ctx, Config): bootstraps TracerProvider, MeterProvider, and LoggerProvider with OTLP gRPC exporters; sets OTel globals
- W3C TraceContext + Baggage propagation set globally
- Resource tagging: service.name, service.version, deployment.environment merged with SDK defaults
- OTLPInsecure bool for development environments without TLS
- Sequential rollback on partial initialization failure — no dangling exporters on error
- Returns shutdown func(context.Context) error; caller defers in main or wires into launcher BeforeStop
- Tier 5 module: must be imported only by application main packages; zero micro-lib dependencies

Tested-via: todo-api POC integration
Reviewed-against: docs/adr/

README.md

@@ -0,0 +1,70 @@
+# telemetry
+
+OTel SDK bootstrap — wires up TracerProvider, MeterProvider, and LoggerProvider with OTLP gRPC exporters pointed at Grafana Alloy (→ Tempo / Mimir / Loki).
+
+**Tier 5 — import only from application `main` packages. Never import from framework libraries.**
+
+## Why Tier 5
+
+Micro-libs use only the OTel API (`go.opentelemetry.io/otel`) which ships a zero-overhead no-op default. This module activates the real SDK and sets the three OTel globals, so all micro-libs using the global API auto-instrument without knowing about this module.
+
+## Installation
+
+```
+require code.nochebuena.dev/go/telemetry v0.1.0
+```
+
+## Usage
+
+```go
+func main() {
+    ctx := context.Background()
+
+    // Bootstrap telemetry before any other component.
+    shutdown, err := telemetry.New(ctx, telemetry.Config{
+        ServiceName:  "order-service",
+        OTLPEndpoint: "alloy:4317",
+        OTLPInsecure: true, // dev only
+    })
+    if err != nil {
+        log.Fatalf("telemetry: %v", err)
+    }
+    defer shutdown(ctx)
+
+    // Start the rest of the application…
+}
+```
+
+## Config
+
+| Field | Env var | Required | Default | Description |
+|---|---|---|---|---|
+| `ServiceName` | `OTEL_SERVICE_NAME` | ✓ | — | Service name in traces/metrics/logs |
+| `ServiceVersion` | `OTEL_SERVICE_VERSION` | | `unknown` | Deployed version |
+| `Environment` | `OTEL_ENVIRONMENT` | | `development` | Deployment environment |
+| `OTLPEndpoint` | `OTEL_EXPORTER_OTLP_ENDPOINT` | ✓ | — | OTLP gRPC address (e.g. `alloy:4317`) |
+| `OTLPInsecure` | `OTEL_EXPORTER_OTLP_INSECURE` | | `false` | Disable TLS (dev only) |
+
+## What `New` sets up
+
+| Signal | SDK | Exporter | Backend |
+|---|---|---|---|
+| Traces | `sdktrace.TracerProvider` | OTLP gRPC | Grafana Alloy → Tempo |
+| Metrics | `sdkmetric.MeterProvider` | OTLP gRPC | Grafana Alloy → Mimir |
+| Logs | `sdklog.LoggerProvider` | OTLP gRPC | Grafana Alloy → Loki |
+
+Also sets `otel.SetTextMapPropagator` with W3C TraceContext + Baggage.
+
+## Shutdown
+
+The returned `func(context.Context) error` flushes all pending telemetry and shuts down the three providers. Always call it before process exit.
+
+```go
+defer func() {
+    shutCtx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+    defer cancel()
+    if err := shutdown(shutCtx); err != nil {
+        log.Printf("telemetry shutdown: %v", err)
+    }
+}()
+```