feat(docker-watcher): phase 7 - deployer & health checker

Deploy orchestrator with full pipeline: pull → create container →
start → network → NPM proxy → health check. Rollback on failure,
multi-instance support, max_instances enforcement, webhook notifications.
Fix NPM auth in rollback and error logging in removeInstance.

internal/api/middleware.go

@@ -0,0 +1,69 @@
+package api
+
+import (
+	"log"
+	"net/http"
+	"runtime/debug"
+	"time"
+)
+
+// logging is an HTTP middleware that logs every request with method, path,
+// status code, and duration.
+func logging(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		start := time.Now()
+		wrapped := &statusRecorder{ResponseWriter: w, status: http.StatusOK}
+
+		next.ServeHTTP(wrapped, r)
+
+		log.Printf("[api] %s %s %d %s", r.Method, r.URL.Path, wrapped.status, time.Since(start))
+	})
+}
+
+// recovery is an HTTP middleware that catches panics and returns a 500 response.
+func recovery(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		defer func() {
+			if err := recover(); err != nil {
+				log.Printf("[api] panic: %v\n%s", err, debug.Stack())
+				respondError(w, http.StatusInternalServerError, "internal server error")
+			}
+		}()
+		next.ServeHTTP(w, r)
+	})
+}
+
+// cors is an HTTP middleware that sets permissive CORS headers for development.
+func cors(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Access-Control-Allow-Origin", "*")
+		w.Header().Set("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS")
+		w.Header().Set("Access-Control-Allow-Headers", "Content-Type, Authorization")
+
+		if r.Method == http.MethodOptions {
+			w.WriteHeader(http.StatusNoContent)
+			return
+		}
+
+		next.ServeHTTP(w, r)
+	})
+}
+
+// jsonContentType is an HTTP middleware that sets the default Content-Type to JSON.
+func jsonContentType(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		next.ServeHTTP(w, r)
+	})
+}
+
+// statusRecorder wraps http.ResponseWriter to capture the status code.
+type statusRecorder struct {
+	http.ResponseWriter
+	status int
+}
+
+func (r *statusRecorder) WriteHeader(code int) {
+	r.status = code
+	r.ResponseWriter.WriteHeader(code)
+}