feat(sqltypes): add nullable SQL types with automatic casting

* Introduced SqlNull type for nullable values with auto-casting.
* Implemented JSON, YAML, and XML marshaling/unmarshaling.
* Added specific types for common SQL types (e.g., SqlInt64, SqlString).
* Included utility functions for creating nullable types.
* Added SqlTimeStamp, SqlDate, and SqlTime types with custom formatting.

go.mod

@@ -3,6 +3,7 @@ module git.warky.dev/wdevs/amcs
 go 1.26.1
 
 require (
+	git.warky.dev/wdevs/relspecgo v1.0.62
 	github.com/bitechdev/ResolveSpec v1.1.26
 	github.com/google/jsonschema-go v0.4.3
 	github.com/google/uuid v1.6.0
@@ -46,7 +47,6 @@ require (
 	github.com/prometheus/procfs v0.20.1 // indirect
 	github.com/puzpuzpuz/xsync/v3 v3.5.1 // indirect
 	github.com/redis/go-redis/v9 v9.19.0 // indirect
-	github.com/rogpeppe/go-internal v1.14.1 // indirect
 	github.com/sagikazarmark/locafero v0.12.0 // indirect
 	github.com/segmentio/asm v1.1.3 // indirect
 	github.com/segmentio/encoding v0.5.4 // indirect