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/debug_env.go

@@ -0,0 +1,9 @@
+//go:build debugenv
+// +build debugenv
+
+package debug
+
+import "os"
+
+// check if debug env variable is set
+var debug = (os.Getenv("DEBUG") != "")