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>

hwsauth/go.mod

@@ -4,16 +4,24 @@ go 1.25.5
 
 require (
 	git.haelnorr.com/h/golib/cookies v0.9.0
-	git.haelnorr.com/h/golib/jwt v0.9.2
+	git.haelnorr.com/h/golib/env v0.9.1
 	git.haelnorr.com/h/golib/hws v0.1.0
+	git.haelnorr.com/h/golib/jwt v0.9.2
 	github.com/pkg/errors v0.9.1
 	github.com/rs/zerolog v1.34.0
 )
 
+replace git.haelnorr.com/h/golib/hws => ../hws
+
 require (
+	git.haelnorr.com/h/golib/hlog v0.9.0 // indirect
+	github.com/go-logr/logr v1.4.3 // indirect
 	github.com/golang-jwt/jwt v3.2.2+incompatible // indirect
 	github.com/google/uuid v1.6.0 // indirect
 	github.com/mattn/go-colorable v0.1.13 // indirect
 	github.com/mattn/go-isatty v0.0.19 // indirect
 	golang.org/x/sys v0.12.0 // indirect
+	k8s.io/apimachinery v0.35.0 // indirect
+	k8s.io/klog/v2 v2.130.1 // indirect
+	k8s.io/utils v0.0.0-20251002143259-bc988d571ff4 // indirect
 )