refactor(pkg): canonicalize base types and adjust length handling

* Update base types to keep explicit modifier forms
* Modify length handling for vector types in tests

pkg/pgsql/types_registry.go

@@ -1,6 +1,9 @@
 package pgsql
 
-import "strings"
+import (
+	"sort"
+	"strings"
+)
 
 // TypeSpec describes PostgreSQL type capabilities used by parsers/writers.
 type TypeSpec struct {
@@ -106,9 +109,9 @@ var postgresBaseTypes = map[string]TypeSpec{
 	"ltree":     {},
 	"lquery":    {},
 	"ltxtquery": {},
-	"vector":    {SupportsLength: true}, // pgvector: vector(dim)
-	"halfvec":   {SupportsLength: true}, // pgvector: halfvec(dim)
-	"sparsevec": {SupportsLength: true}, // pgvector: sparsevec(dim)
+	"vector":    {}, // pgvector: keep explicit modifier form (vector(dim))
+	"halfvec":   {}, // pgvector: keep explicit modifier form (halfvec(dim))
+	"sparsevec": {}, // pgvector: keep explicit modifier form (sparsevec(dim))
 }
 
 var postgresTypeAliases = map[string]string{
@@ -148,6 +151,7 @@ func GetPostgresBaseTypes() []string {
 	for t := range postgresBaseTypes {
 		result = append(result, t)
 	}
+	sort.Strings(result)
 	return result
 }
 

pkg/pgsql/types_registry_test.go

@@ -53,7 +53,7 @@ func TestPostgresTypeRegistry_TypeParsingAndCapabilities(t *testing.T) {
 			wantBase:          "vector",
 			wantCanonicalBase: "vector",
 			wantKnown:         true,
-			wantLength:        true,
+			wantLength:        false,
 		},
 		{
 			input:             "numeric(10,2)",