feat(config): add TOML configuration system with wildcard pattern matching

- Add .shush.toml config file discovery (project > git root > global)
- Support exact patterns (TODO:, @ts-ignore) and wildcards (*IMPORTANT*)
- Include smart defaults for common comment preservation patterns
- Add config validation and example file generation

internal/config/config.go

@@ -0,0 +1,227 @@
+package config
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/BurntSushi/toml"
+)
+
+
+type Config struct {
+	Preserve []string `toml:"preserve"`
+}
+
+
+func Default() *Config {
+	return &Config{
+		Preserve: []string{
+			"TODO:",
+			"FIXME:",
+			"HACK:",
+			"XXX:",
+			"@ts-ignore",
+			"@ts-expect-error",
+			"eslint-",
+			"prettier-ignore",
+			"pylint:",
+			"mypy:",
+			"type: ignore",
+		},
+	}
+}
+
+
+func Load() (*Config, string, error) {
+
+	if configPath, found := findProjectConfig(); found {
+		config, err := loadFromFile(configPath)
+		if err != nil {
+			return Default(), configPath, err
+		}
+		return config, configPath, nil
+	}
+
+
+	if configPath, found := findGlobalConfig(); found {
+		config, err := loadFromFile(configPath)
+		if err != nil {
+			return Default(), configPath, err
+		}
+		return config, configPath, nil
+	}
+
+
+	return Default(), "", nil
+}
+
+
+func findProjectConfig() (string, bool) {
+
+	cwd, err := os.Getwd()
+	if err != nil {
+		return "", false
+	}
+
+	localConfig := filepath.Join(cwd, ".shush.toml")
+	if fileExists(localConfig) {
+		return localConfig, true
+	}
+
+
+	if gitRoot := findGitRoot(cwd); gitRoot != "" {
+		gitConfig := filepath.Join(gitRoot, ".shush.toml")
+		if fileExists(gitConfig) && gitConfig != localConfig {
+			return gitConfig, true
+		}
+	}
+
+	return "", false
+}
+
+
+func findGlobalConfig() (string, bool) {
+	home, err := os.UserHomeDir()
+	if err != nil {
+		return "", false
+	}
+
+	configPath := filepath.Join(home, ".config", ".shush.toml")
+	if fileExists(configPath) {
+		return configPath, true
+	}
+
+	return "", false
+}
+
+
+func findGitRoot(startDir string) string {
+	dir := startDir
+	for {
+		gitDir := filepath.Join(dir, ".git")
+		if fileExists(gitDir) {
+			return dir
+		}
+
+		parent := filepath.Dir(dir)
+		if parent == dir {
+break
+		}
+		dir = parent
+	}
+	return ""
+}
+
+
+func loadFromFile(path string) (*Config, error) {
+	config := &Config{}
+	if _, err := toml.DecodeFile(path, config); err != nil {
+		return nil, err
+	}
+	
+
+	if len(config.Preserve) == 0 {
+		config.Preserve = Default().Preserve
+	}
+	
+	return config, nil
+}
+
+
+func fileExists(path string) bool {
+	_, err := os.Stat(path)
+	return err == nil
+}
+
+
+func (c *Config) ShouldPreserveComment(comment string) bool {
+	comment = strings.TrimSpace(comment)
+	
+	for _, pattern := range c.Preserve {
+		if matchesPattern(comment, pattern) {
+			return true
+		}
+	}
+	
+	return false
+}
+
+
+func matchesPattern(text, pattern string) bool {
+
+	if strings.Contains(pattern, "*") {
+		return matchesWildcard(text, pattern)
+	}
+	
+
+	return strings.Contains(text, pattern)
+}
+
+
+func matchesWildcard(text, pattern string) bool {
+
+	parts := strings.Split(pattern, "*")
+	
+
+	if !strings.HasPrefix(pattern, "*") {
+		if !strings.HasPrefix(text, parts[0]) {
+			return false
+		}
+		text = text[len(parts[0]):]
+		parts = parts[1:]
+	} else {
+parts = parts[1:]
+	}
+	
+
+	if !strings.HasSuffix(pattern, "*") && len(parts) > 0 {
+		lastPart := parts[len(parts)-1]
+		if !strings.HasSuffix(text, lastPart) {
+			return false
+		}
+		text = text[:len(text)-len(lastPart)]
+		parts = parts[:len(parts)-1]
+	}
+	
+
+	for _, part := range parts {
+		if part == "" {
+continue
+		}
+		
+		index := strings.Index(text, part)
+		if index == -1 {
+			return false
+		}
+		
+
+		text = text[index+len(part):]
+	}
+	
+	return true
+}
+
+
+func CreateExampleConfig() error {
+	content := `# Shush Configuration
+# Patterns to preserve in comments (supports wildcards with *)
+preserve = [
+    "TODO:",
+    "FIXME:", 
+    "HACK:",
+    "XXX:",
+    "@ts-ignore",
+    "@ts-expect-error", 
+    "eslint-",
+    "prettier-ignore",
+    "pylint:",
+    "mypy:",
+    "type: ignore",
+    "*IMPORTANT*",   # Example wildcard: preserves any comment containing IMPORTANT
+    "*DEBUG*",       # Example wildcard: preserves any comment containing DEBUG
+]
+`
+	
+	return os.WriteFile(".shush.toml", []byte(content), 0644)
+}