enhance: thread-safe CookieJar, SameSite cookie attr, dynamic Google countries

- Wrap staticCookieJar in struct with sync.RWMutex for thread safety
- Add SameSite field to Cookie struct with Strict/Lax/None constants
- Update Playwright cookie conversion functions for SameSite
- Replace hardcoded 4-country switch with dynamic country code generation

Closes #20, #22, #23
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cookies_txt.go

@@ -6,21 +6,32 @@ import (
 	"os"
 	"strconv"
 	"strings"
+	"sync"
 	"time"
 )
 
-type staticCookieJar []Cookie
+type staticCookieJar struct {
+	mu      sync.RWMutex
+	cookies []Cookie
+}
 
 // GetAll will return all cookies in the jar.
 func (s *staticCookieJar) GetAll() ([]Cookie, error) {
-	return *s, nil
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	out := make([]Cookie, len(s.cookies))
+	copy(out, s.cookies)
+	return out, nil
 }
 
 // Get will, given a URL, return all cookies that are valid for that URL.
 func (s *staticCookieJar) Get(target string) ([]Cookie, error) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
 	var validCookies []Cookie
 
-	for _, cookie := range *s {
+	for _, cookie := range s.cookies {
 		if match, err := cookie.IsTargetMatch(target); err != nil {
 			return nil, err
 		} else if match {
@@ -32,22 +43,28 @@ func (s *staticCookieJar) Get(target string) ([]Cookie, error) {
 }
 
 func (s *staticCookieJar) Set(cookie Cookie) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
 	// see if the cookie already exists
-	for i, c := range *s {
+	for i, c := range s.cookies {
 		if c.Name == cookie.Name && c.Host == cookie.Host && c.Path == cookie.Path {
-			(*s)[i] = cookie
+			s.cookies[i] = cookie
 			return nil
 		}
 	}
 
-	*s = append(*s, cookie)
+	s.cookies = append(s.cookies, cookie)
 	return nil
 }
 
 func (s *staticCookieJar) Delete(cookie Cookie) error {
-	for i, c := range *s {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	for i, c := range s.cookies {
 		if c.Name == cookie.Name && c.Host == cookie.Host && c.Path == cookie.Path {
-			*s = append((*s)[:i], (*s)[i+1:]...)
+			s.cookies = append(s.cookies[:i], s.cookies[i+1:]...)
 			return nil
 		}
 	}
@@ -66,7 +83,7 @@ func LoadCookiesFile(path string) (CookieJar, error) {
 		_ = cl.Close()
 	}(fp)
 
-	var cookies staticCookieJar
+	var cookies []Cookie
 
 	scanner := bufio.NewScanner(fp)
 
@@ -102,5 +119,5 @@ func LoadCookiesFile(path string) (CookieJar, error) {
 		})
 	}
 
-	return &cookies, nil
+	return &staticCookieJar{cookies: cookies}, nil
 }