Refactor database interface to use *sql.DB directly

Simplified the database layer by removing custom interface wrappers
and using standard library *sql.DB and *sql.Tx types directly.

Changes:
- Removed DBConnection and DBTransaction interfaces from database.go
- Removed NewDBConnection() wrapper function
- Updated TokenGenerator to use *sql.DB instead of DBConnection
- Updated all validation and revocation methods to accept *sql.Tx
- Updated TableManager to work with *sql.DB directly
- Updated all tests to use db.Begin() instead of custom wrappers
- Fixed GeneratorConfig.DB field (was DBConn)
- Updated documentation in doc.go with correct API usage

Benefits:
- Simpler API with fewer abstractions
- Works directly with database/sql standard library
- Compatible with GORM (via gormDB.DB()) and Bun (share same *sql.DB)
- Easier to understand and maintain
- No unnecessary wrapper layers

Breaking changes:
- GeneratorConfig.DBConn renamed to GeneratorConfig.DB
- Removed NewDBConnection() function - pass *sql.DB directly
- ValidateAccess/ValidateRefresh now accept *sql.Tx instead of DBTransaction
- Token.Revoke/CheckNotRevoked now accept *sql.Tx instead of DBTransaction

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

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

jwt/README.md

@@ -0,0 +1,102 @@
+# JWT Package
+
+[![Go Reference](https://pkg.go.dev/badge/git.haelnorr.com/h/golib/jwt.svg)](https://pkg.go.dev/git.haelnorr.com/h/golib/jwt)
+
+JWT (JSON Web Token) generation and validation with database-backed token revocation support.
+
+## Features
+
+- 🔐 Access and refresh token generation
+- ✅ Token validation with expiration checking
+- 🚫 Token revocation via database blacklist
+- 🗄️ Multi-database support (PostgreSQL, MySQL, SQLite, MariaDB)
+- 🔧 Compatible with database/sql, GORM, and Bun
+- 🤖 Automatic table creation and management
+- 🧹 Database-native automatic cleanup
+- 🔄 Token freshness tracking
+- 💾 "Remember me" functionality
+
+## Installation
+
+```bash
+go get git.haelnorr.com/h/golib/jwt
+```
+
+## Quick Start
+
+```go
+package main
+
+import (
+    "database/sql"
+    "git.haelnorr.com/h/golib/jwt"
+    _ "github.com/lib/pq"
+)
+
+func main() {
+    // Open database
+    db, _ := sql.Open("postgres", "postgres://user:pass@localhost/db")
+    defer db.Close()
+
+    // Wrap database connection
+    dbConn := jwt.NewDBConnection(db)
+
+    // Create token generator
+    gen, err := jwt.CreateGenerator(jwt.GeneratorConfig{
+        AccessExpireAfter:  15,   // 15 minutes
+        RefreshExpireAfter: 1440, // 24 hours
+        FreshExpireAfter:   5,    // 5 minutes
+        TrustedHost:        "example.com",
+        SecretKey:          "your-secret-key",
+        DBConn:             dbConn,
+        DBType: jwt.DatabaseType{
+            Type:    jwt.DatabasePostgreSQL,
+            Version: "15",
+        },
+        TableConfig: jwt.DefaultTableConfig(),
+    })
+    if err != nil {
+        panic(err)
+    }
+
+    // Generate tokens
+    accessToken, _, _ := gen.NewAccess(42, true, false)
+    refreshToken, _, _ := gen.NewRefresh(42, false)
+
+    // Validate token
+    tx, _ := dbConn.BeginTx(context.Background(), nil)
+    token, _ := gen.ValidateAccess(tx, accessToken)
+    
+    // Revoke token
+    token.Revoke(tx)
+    tx.Commit()
+}
+```
+
+## Documentation
+
+Comprehensive documentation is available in the [Wiki](https://git.haelnorr.com/h/golib/wiki/JWT).
+
+### Key Topics
+
+- [Configuration](https://git.haelnorr.com/h/golib/wiki/JWT#configuration)
+- [Token Generation](https://git.haelnorr.com/h/golib/wiki/JWT#token-generation)
+- [Token Validation](https://git.haelnorr.com/h/golib/wiki/JWT#token-validation)
+- [Token Revocation](https://git.haelnorr.com/h/golib/wiki/JWT#token-revocation)
+- [Cleanup](https://git.haelnorr.com/h/golib/wiki/JWT#cleanup)
+- [Using with ORMs](https://git.haelnorr.com/h/golib/wiki/JWT#using-with-orms)
+
+## Supported Databases
+
+- PostgreSQL
+- MySQL
+- MariaDB
+- SQLite
+
+## License
+
+See LICENSE file in the repository root.
+
+## Contributing
+
+Contributions are welcome! Please open an issue or submit a pull request.