feat: iris uninstall command (#21)

New uninstall command option
```bash
IRIS uninstall
```

Fix install and uninstall script

root/uninstall.go

@@ -0,0 +1,147 @@
+package root
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/spf13/cobra"
+	"github.com/versenilvis/iris/config"
+)
+
+func init() {
+	rootCmd.AddCommand(uninstallCmd)
+}
+
+var uninstallCmd = &cobra.Command{
+	Use:   "uninstall",
+	Short: "Uninstall Iris and remove shell integrations",
+	Run: func(cmd *cobra.Command, args []string) {
+		fmt.Println("Uninstalling Iris...")
+		home, err := os.UserHomeDir()
+		if err != nil {
+			fmt.Printf("! could not determine home directory: %v\n", err)
+			return
+		}
+
+		configFiles := []string{
+			filepath.Join(home, ".zshrc"),
+			filepath.Join(home, ".bashrc"),
+			filepath.Join(home, ".config", "fish", "config.fish"),
+		}
+
+		for _, file := range configFiles {
+			if cleanShellConfig(file) {
+				fmt.Printf("✓ Removed integration from %s\n", file)
+			}
+		}
+
+		// Remove config, state, and cache directories
+		if cfgPath, err := config.ConfigPath(); err == nil {
+			if cfgDir := filepath.Dir(cfgPath); os.RemoveAll(cfgDir) == nil {
+				fmt.Printf("✓ Removed config directory: %s\n", cfgDir)
+			}
+		}
+		if statePath, err := config.StatePath(); err == nil {
+			if stateDir := filepath.Dir(statePath); os.RemoveAll(stateDir) == nil {
+				fmt.Printf("✓ Removed state directory: %s\n", stateDir)
+			}
+		}
+		if cachePath, err := config.CachePath(); err == nil {
+			if os.RemoveAll(cachePath) == nil {
+				fmt.Printf("✓ Removed cache directory: %s\n", cachePath)
+			}
+		}
+
+		binLocations := []string{
+			filepath.Join(home, ".local", "bin", "iris"),
+			"/usr/local/bin/iris",
+		}
+		if exe, err := os.Executable(); err == nil && exe != "" {
+			binLocations = append(binLocations, exe)
+		}
+
+		anyFound := false
+		for _, loc := range binLocations {
+			if _, err := os.Stat(loc); err == nil {
+				anyFound = true
+				if errRemove := os.Remove(loc); errRemove == nil {
+					fmt.Printf("✓ Removed binary: %s\n", loc)
+				} else {
+					fmt.Printf("! Could not remove binary at %s (try with sudo): %v\n", loc, errRemove)
+				}
+			}
+		}
+
+		if !anyFound {
+			fmt.Println("✓ No leftover binary files found")
+		}
+
+		_ = os.Remove("iris.log")
+
+		fmt.Println("\n✓ Iris has been successfully uninstalled")
+		if os.Getenv("IRIS_PID") != "" {
+			fmt.Println("\n⚠️  You are currently inside an active Iris session.")
+			fmt.Println("Iris runs as the parent process of this terminal - do NOT run 'pkill iris'")
+			fmt.Println("as it will immediately close this terminal window.")
+			fmt.Println("\nTo fully exit, simply close this terminal window and open a new one.")
+			fmt.Println("Iris will not start again since the shell config has been cleaned up.")
+		} else {
+			fmt.Println("Please close and reopen your terminal to complete the uninstall.")
+		}
+	},
+}
+
+func cleanShellConfig(filePath string) bool {
+	content, err := os.ReadFile(filePath)
+	if err != nil {
+		return false
+	}
+
+	var lines []string
+	scanner := bufio.NewScanner(strings.NewReader(string(content)))
+	modified := false
+	skipNext := false
+
+	for scanner.Scan() {
+		line := scanner.Text()
+		if skipNext {
+			skipNext = false
+			modified = true
+			continue
+		}
+		lowerLine := strings.ToLower(line)
+		if strings.Contains(lowerLine, "# iris autocomplete") || strings.Contains(lowerLine, "# iris autostart") {
+			modified = true
+			skipNext = true
+			continue
+		}
+		if strings.Contains(lowerLine, "iris init") {
+			modified = true
+			continue
+		}
+		lines = append(lines, line)
+	}
+
+	if scanErr := scanner.Err(); scanErr != nil {
+		return false
+	}
+
+	if !modified {
+		return false
+	}
+
+	for len(lines) > 0 && strings.TrimSpace(lines[len(lines)-1]) == "" {
+		lines = lines[:len(lines)-1]
+	}
+
+	output := strings.Join(lines, "\n")
+	if len(lines) > 0 {
+		output += "\n"
+	}
+
+	err = os.WriteFile(filePath, []byte(output), 0644)
+	return err == nil
+}