Fix: Add missing cmd/repogen/main.go and update .gitignore

The cmd/repogen/main.go file was accidentally ignored by .gitignore
because the pattern "repogen" was matching the directory name.

Changes:
- Change .gitignore pattern from "repogen" to "/repogen" to only
  ignore the binary in the root directory
- Add cmd/repogen/main.go that was previously ignored

This fixes the GitHub Actions failures where workflows couldn't
find the main.go file to build.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: ralt

.gitignore

@@ -1,5 +1,5 @@
 # Binaries
-repogen
+/repogen
 *.exe
 *.dll
 *.so

cmd/repogen/main.go

@@ -0,0 +1,21 @@
+package main
+
+import (
+	"os"
+
+	"github.com/ralt/repogen/internal/cli"
+	"github.com/sirupsen/logrus"
+)
+
+func main() {
+	// Setup logging format
+	logrus.SetFormatter(&logrus.TextFormatter{
+		FullTimestamp: true,
+	})
+
+	rootCmd := cli.NewRootCmd()
+	if err := rootCmd.Execute(); err != nil {
+		logrus.Error(err)
+		os.Exit(1)
+	}
+}