Adopt repo standards: scaffold, policies, lint-clean (closes #1)

Standard scaffold: script/ entrypoints with the Makefile as thin shims, a Dockerfile whose lint and test phases gate the build, a Gitea CI workflow running script/cibuild, REPO_POLICIES.md, TODO.md, .editorconfig, .dockerignore, LICENSE, wider .gitignore. .golangci.yml is byte-identical to the canonical copy in the prompts repo.

211 lint findings fixed in code: package globals became functions/fields and a cobra command constructor, magic numbers became named constants, ctx is threaded into the probes, monitor loops split. Tests moved to external _test packages with export_test.go. Behavior unchanged.

Readers will trip over: make lint/test/check now need a Docker daemon; the personal rsync copy/run targets are gone and make run runs locally.
Disclosure: four //nolint:gosec remain on the fixed-argv ping/curl calls and the operator-chosen log file, as the reference repo annotates the same class.
Disclosure: module path left as-is.

Model: opus-4-8 (implementation); fable-5-1 (merge)

internal/cli/root_test.go

@@ -1,36 +1,25 @@
 //go:build linux
-// +build linux
 
-package cli
+package cli_test
 
 import (
 	"testing"
+
+	"git.eeqj.de/sneak/rtnetmon/internal/cli"
 )
 
-// TestExecute tests that the CLI can be initialized
-func TestExecute(t *testing.T) {
-	// This is a simple compilation test to ensure the CLI package compiles
-	// We can't easily test the full Execute() function as it starts the UI
+func TestNewRootCmd(t *testing.T) {
+	t.Parallel()
 
-	// Test that rootCmd is properly initialized
-	if rootCmd == nil {
-		t.Fatal("rootCmd is nil")
+	cmd := cli.NewRootCmd()
+	if cmd.Use != "rtnetmon" {
+		t.Errorf("Use = %q, want %q", cmd.Use, "rtnetmon")
 	}
 
-	if rootCmd.Use != "rtnetmon" {
-		t.Errorf("Expected rootCmd.Use to be 'rtnetmon', got '%s'", rootCmd.Use)
-	}
-
-	// Test that default configuration is set
-	if len(defaultReachabilityHosts) == 0 {
-		t.Error("defaultReachabilityHosts is empty")
-	}
-
-	if len(defaultPacketLossHosts) == 0 {
-		t.Error("defaultPacketLossHosts is empty")
-	}
-
-	if len(defaultTCPHosts) == 0 {
-		t.Error("defaultTCPHosts is empty")
+	names := []string{"ifaceA", "labelA", "ifaceB", "labelB", "hosts", "logfile"}
+	for _, name := range names {
+		if cmd.Flags().Lookup(name) == nil {
+			t.Errorf("flag %q not registered", name)
+		}
 	}
 }