Add support for running profiling when debug build-tags provided (#491)

* wrap root HTTP handler in debug.WithPprof(), rearrange router.Start() to support this
* remove unused code
* set debug buildtag in build script when $DEBUG set
* update go-debug version with fixed handler
* use clone of router.srv for LE cert manager, reset server timeouts in debug
* add kim's other libraries to README

vendor/codeberg.org/gruf/go-debug/pprof_off.go

@@ -0,0 +1,16 @@
+//go:build !debug && !debugenv
+// +build !debug,!debugenv
+
+package debug
+
+import "net/http"
+
+// ServePprof will start an HTTP server serving /debug/pprof only if debug enabled.
+func ServePprof(addr string) error {
+	return nil
+}
+
+// WithPprof will add /debug/pprof handling (provided by "net/http/pprof") only if debug enabled.
+func WithPprof(handler http.Handler) http.Handler {
+	return handler
+}