Add Nix flake for mcrctl

Vendor dependencies and expose mcrctl binary via nix build.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

vendor/github.com/go-chi/chi/v5/middleware/profiler.go

@@ -0,0 +1,49 @@
+//go:build !tinygo
+// +build !tinygo
+
+package middleware
+
+import (
+	"expvar"
+	"net/http"
+	"net/http/pprof"
+
+	"github.com/go-chi/chi/v5"
+)
+
+// Profiler is a convenient subrouter used for mounting net/http/pprof. ie.
+//
+//	func MyService() http.Handler {
+//		r := chi.NewRouter()
+//		// ..middlewares
+//		r.Mount("/debug", middleware.Profiler())
+//		// ..routes
+//		return r
+//	}
+func Profiler() http.Handler {
+	r := chi.NewRouter()
+	r.Use(NoCache)
+
+	r.Get("/", func(w http.ResponseWriter, r *http.Request) {
+		http.Redirect(w, r, r.RequestURI+"/pprof/", http.StatusMovedPermanently)
+	})
+	r.HandleFunc("/pprof", func(w http.ResponseWriter, r *http.Request) {
+		http.Redirect(w, r, r.RequestURI+"/", http.StatusMovedPermanently)
+	})
+
+	r.HandleFunc("/pprof/*", pprof.Index)
+	r.HandleFunc("/pprof/cmdline", pprof.Cmdline)
+	r.HandleFunc("/pprof/profile", pprof.Profile)
+	r.HandleFunc("/pprof/symbol", pprof.Symbol)
+	r.HandleFunc("/pprof/trace", pprof.Trace)
+	r.Handle("/vars", expvar.Handler())
+
+	r.Handle("/pprof/goroutine", pprof.Handler("goroutine"))
+	r.Handle("/pprof/threadcreate", pprof.Handler("threadcreate"))
+	r.Handle("/pprof/mutex", pprof.Handler("mutex"))
+	r.Handle("/pprof/heap", pprof.Handler("heap"))
+	r.Handle("/pprof/block", pprof.Handler("block"))
+	r.Handle("/pprof/allocs", pprof.Handler("allocs"))
+
+	return r
+}