chore(ci): add govulncheck, staticcheck, go vet, gofumpt gates

* Add lint/format checks to the Gitea release workflow and Makefile
  (targets: vet, fmt, fmt-check, staticcheck, govulncheck, check)
* Switch .golangci.json formatter from gofmt to gofumpt (extra.group-params)
* Bump golang.org/x/text 0.37.0 -> 0.39.0 for GO-2026-5970; re-vendor
* Fix staticcheck S1011 in pkg/diff; drop unused pgsql writer helpers
* Fix gocritic unnamedResult (pkg/diff) and rangeValCopy (pkg/pgsql)
* Apply gofumpt + goimports formatting across the tree

pkg/readers/bun/reader.go

@@ -245,7 +245,7 @@ func (r *Reader) getReceiverType(expr ast.Expr) string {
 }
 
 // parseTableNameMethod parses a TableName() method and extracts the table and schema name
-func (r *Reader) parseTableNameMethod(funcDecl *ast.FuncDecl) (tableName string, schemaName string) {
+func (r *Reader) parseTableNameMethod(funcDecl *ast.FuncDecl) (tableName, schemaName string) {
 	if funcDecl.Body == nil {
 		return "", ""
 	}
@@ -578,7 +578,7 @@ func (r *Reader) parseIndexesFromTag(table *models.Table, column *models.Column,
 }
 
 // extractTableNameFromTag extracts table and schema from bun tag
-func (r *Reader) extractTableNameFromTag(tag string) (tableName string, schemaName string) {
+func (r *Reader) extractTableNameFromTag(tag string) (tableName, schemaName string) {
 	// Extract bun tag value
 	re := regexp.MustCompile(`bun:"table:([^"]+)"`)
 	matches := re.FindStringSubmatch(tag)
@@ -712,12 +712,12 @@ func (r *Reader) parseTypeWithLength(typeStr string) (baseType string, length in
 		if pgsql.SupportsLength(rawBaseType) {
 			if _, err := fmt.Sscanf(matches[2], "%d", &length); err == nil {
 				baseType = pgsql.CanonicalizeBaseType(rawBaseType)
-				return
+				return baseType, length
 			}
 		}
 	}
 
-	return
+	return baseType, length
 }
 
 // goTypeToSQL maps Go types to SQL types