chore(runtime): Add logrus logging framework with structured logging

Add logrus as the primary logging framework with dependency injection
pattern. All errors now use WithError() for context, and structured
logging uses camelCase field names. Tag runtime service with service
field for better log organization.

- Add logrus dependency
- Update Runtime to accept logger via dependency injection
- Add WithLogger() option for logger configuration
- Log errors with WithError() for context
- Log async function failures with service context
- Document logging practices in AGENTS.md

internal/runtime/options.go

@@ -1,6 +1,10 @@
 package runtime
 
-import "io"
+import (
+	"io"
+
+	"github.com/sirupsen/logrus"
+)
 
 type RuntimeOption func(*Runtime)
 
@@ -17,3 +21,9 @@ func WithStderr(stderr io.Writer) RuntimeOption {
 		r.opts.Stderr = stderr
 	}
 }
+
+func WithLogger(logger *logrus.Logger) RuntimeOption {
+	return func(r *Runtime) {
+		r.logger = logger.WithField("service", "runtime")
+	}
+}

internal/runtime/runtime.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/evanw/esbuild/pkg/api"
 	"github.com/fastschema/qjs"
+	"github.com/sirupsen/logrus"
 
 	"reichard.io/poiesis/internal/functions"
 	_ "reichard.io/poiesis/internal/stdlib"
@@ -18,11 +19,13 @@ type Runtime struct {
 	opts      qjs.Option
 	funcs     map[string]functions.Function
 	typeDecls map[string]string
+	logger    *logrus.Entry
 }
 
 func New(ctx context.Context, opts ...RuntimeOption) (*Runtime, error) {
 	// Create Runtime
-	r := &Runtime{opts: qjs.Option{Context: ctx}}
+	logger := logrus.New()
+	r := &Runtime{opts: qjs.Option{Context: ctx}, logger: logger.WithField("service", "runtime")}
 	for _, opt := range opts {
 		opt(r)
 	}
@@ -30,12 +33,14 @@ func New(ctx context.Context, opts ...RuntimeOption) (*Runtime, error) {
 	// Create QuickJS Context
 	rt, err := qjs.New(r.opts)
 	if err != nil {
+		logger.WithError(err).Error("Failed to create QuickJS context")
 		return nil, err
 	}
 	r.ctx = rt.Context()
 
 	// Populate Globals
 	if err := r.populateGlobals(); err != nil {
+		logger.WithError(err).Error("Failed to populate globals")
 		return nil, err
 	}
 
@@ -62,6 +67,7 @@ func (r *Runtime) populateGlobals() error {
 			r.ctx.SetAsyncFunc(name, func(this *qjs.This) {
 				qjsVal, err := callFunc(this, fn)
 				if err != nil {
+					r.logger.WithError(err).Errorf("Async function %s failed", name)
 					_ = this.Promise().Reject(this.Context().NewError(err))
 					return
 				}