Update JWT documentation for BeginTX pattern

Updated all code examples to reflect the new generator API that accepts
a BeginTX function instead of managing database connections directly.

Changes include:
- Updated Basic Setup example with txGetter function
- Updated Without Database example
- Updated GORM integration example
- Updated Bun integration example
- Updated Complete Example

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

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

JWT.md

@@ -27,6 +27,7 @@ go get git.haelnorr.com/h/golib/jwt
 package main
 
 import (
+    "context"
     "database/sql"
     "git.haelnorr.com/h/golib/jwt"
     _ "github.com/lib/pq"
@@ -40,6 +41,11 @@ func main() {
     }
     defer db.Close()
 
+    // Create a transaction getter function
+    txGetter := func(ctx context.Context) (jwt.DBTransaction, error) {
+        return db.Begin()
+    }
+
     // Create token generator
     gen, err := jwt.CreateGenerator(jwt.GeneratorConfig{
         AccessExpireAfter:  15,   // Access tokens expire in 15 minutes
@@ -53,7 +59,7 @@ func main() {
             Version: "15",
         },
         TableConfig: jwt.DefaultTableConfig(),
-    })
+    }, txGetter)
     if err != nil {
         panic(err)
     }
@@ -74,8 +80,8 @@ gen, err := jwt.CreateGenerator(jwt.GeneratorConfig{
     FreshExpireAfter:   5,
     TrustedHost:        "example.com",
     SecretKey:          "your-secret-key-here",
-    DBConn:             nil, // No database = no revocation
-})
+    DB:                 nil, // No database = no revocation
+}, nil) // nil transaction getter since no DB
 ```
 
 ## Configuration
@@ -389,6 +395,7 @@ GORM transactions can be used directly with the JWT package:
 
 ```go
 import (
+    "context"
     "gorm.io/gorm"
     "gorm.io/driver/postgres"
 )
@@ -397,6 +404,11 @@ import (
 gormDB, _ := gorm.Open(postgres.Open(dsn), &gorm.Config{})
 sqlDB, _ := gormDB.DB()
 
+// Create a transaction getter function
+txGetter := func(ctx context.Context) (jwt.DBTransaction, error) {
+    return sqlDB.Begin()
+}
+
 // Create generator with sql.DB
 gen, _ := jwt.CreateGenerator(jwt.GeneratorConfig{
     AccessExpireAfter:  15,
@@ -410,7 +422,7 @@ gen, _ := jwt.CreateGenerator(jwt.GeneratorConfig{
         Version: "15",
     },
     TableConfig: jwt.DefaultTableConfig(),
-})
+}, txGetter)
 
 // Option 1: Use GORM transactions directly
 tx := gormDB.Begin()
@@ -443,6 +455,11 @@ sqlDB := sql.Open(pgdriver.NewConnector(pgdriver.WithDSN(dsn)))
 // Pass sql.DB to both Bun and JWT generator
 bunDB := bun.NewDB(sqlDB, pgdialect.New())
 
+// Create a transaction getter function
+txGetter := func(ctx context.Context) (jwt.DBTransaction, error) {
+    return sqlDB.Begin()
+}
+
 // Create generator with the same sql.DB
 gen, _ := jwt.CreateGenerator(jwt.GeneratorConfig{
     AccessExpireAfter:  15,
@@ -456,7 +473,7 @@ gen, _ := jwt.CreateGenerator(jwt.GeneratorConfig{
         Version: "15",
     },
     TableConfig: jwt.DefaultTableConfig(),
-})
+}, txGetter)
 
 // Option 1: Use Bun transactions directly (recommended)
 ctx := context.Background()
@@ -494,6 +511,11 @@ func main() {
     }
     defer db.Close()
 
+    // Create a transaction getter function
+    txGetter := func(ctx context.Context) (jwt.DBTransaction, error) {
+        return db.Begin()
+    }
+
     // Create token generator
     gen, err := jwt.CreateGenerator(jwt.GeneratorConfig{
         AccessExpireAfter:  15,
@@ -507,7 +529,7 @@ func main() {
             Version: "15",
         },
         TableConfig: jwt.DefaultTableConfig(),
-    })
+    }, txGetter)
     if err != nil {
         panic(err)
     }