feat(ui): print releaser name and version header on every run

Adds a logHeader() helper that prints "releaser  v<version>" to stderr
at the start of every invocation, before any other output.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cmd/main.go

@@ -205,6 +205,8 @@ func initConfig(absRepo string) error {
 }
 
 func run(o options) error {
+	logHeader(version)
+
 	// --- Config ---
 	absRepo, err := filepath.Abs(o.repoPath)
 	if err != nil {

cmd/ui.go

@@ -49,6 +49,13 @@ func logWarn(format string, args ...any) {
 	fmt.Fprintf(os.Stderr, "  %s %s\n", paint(ansiYellow, "!"), msg)
 }
 
+// logHeader prints the tool name and version banner to stderr.
+func logHeader(ver string) {
+	fmt.Fprintf(os.Stderr, "%s  %s\n",
+		paint(ansiBold, "releaser"),
+		paint(ansiDim, "v"+ver))
+}
+
 // logSection writes a bold section header to stderr (used in verbose mode).
 func logSection(title string) {
 	fmt.Fprintf(os.Stderr, "\n%s\n", paint(ansiBold, "▸ "+title))