fix(common): harden CORS, sort, raw-SQL WHERE and x-custom-sql-or

Add a `hardening` config section (RESOLVESPEC_HARDENING_*) so each
fix can be switched off to restore the previous behaviour:

- cors_strict_origins: only reflect origins listed in
  cors.allowed_origins / server URLs, with credentials; `*` never
  sends credentials; fix shared-slice append of expose headers.
- sort_strict: join aliases must match `alias.identifier` (empty alias
  no longer matches everything); sort expressions reject dangerous
  functions/catalogs; cql* columns must be identifier-safe.
- sql_strict: client raw-SQL fragments must have balanced parens and
  quotes, no comments/`;`/`$$`, DML keywords, dangerous functions or
  system catalogs; a rejected fragment now fails closed ("(1=0)")
  instead of dropping the filter. Subqueries stay allowed unless
  sql_block_subqueries is set.
- x-custom-sql-or is grouped together with the client's own
  conditions (new optional WhereGrouper, implemented for bun and gorm)
  so it can no longer OR past server-side filters.

pkg/common/sql_helpers_test.go

@@ -102,25 +102,25 @@ func TestSanitizeWhereClause(t *testing.T) {
 			name:      "dangerous DELETE keyword - blocked",
 			where:     "status = 'active'; DELETE FROM users",
 			tableName: "users",
-			expected:  "",
+			expected:  "(1=0)", // fail closed,
 		},
 		{
 			name:      "dangerous UPDATE keyword - blocked",
 			where:     "1=1; UPDATE users SET admin = true",
 			tableName: "users",
-			expected:  "",
+			expected:  "(1=0)", // fail closed,
 		},
 		{
 			name:      "dangerous TRUNCATE keyword - blocked",
 			where:     "status = 'active' OR TRUNCATE TABLE users",
 			tableName: "users",
-			expected:  "",
+			expected:  "(1=0)", // fail closed,
 		},
 		{
 			name:      "dangerous DROP keyword - blocked",
 			where:     "status = 'active'; DROP TABLE users",
 			tableName: "users",
-			expected:  "",
+			expected:  "(1=0)", // fail closed,
 		},
 		{
 			name:      "subquery with table alias should not be modified",