term: eliminate 'semijoin' and 'antijoin' terminology

Replace deprecated SQL-derived terms with accurate DataJoint terminology:
- 'semijoin/antijoin' → 'restriction/anti-restriction'
- Clarify that A & B restricts A (does not join attributes)

Changes in source code comments:
- expression.py:1081: 'antijoin' → 'anti-restriction'
- condition.py:296: '(semijoin/antijoin)' → 'for restriction'
- condition.py:401: '(aka semijoin and antijoin)' → removed

Rationale: In relational algebra, joins combine attributes from both operands.
DataJoint's A & B restricts A to matching entities—no attributes from B appear
in the result. This is fundamentally restriction, not a join operation.

Author: dimitri-yatsenko

src/datajoint/condition.py

@@ -293,7 +293,7 @@ def make_condition(
     - ``str``: Used directly as SQL condition
     - ``dict``: AND of equality conditions for matching attributes
     - ``bool``: Returns the boolean value (possibly negated)
-    - ``QueryExpression``: Generates subquery (semijoin/antijoin)
+    - ``QueryExpression``: Generates subquery for restriction
     - ``AndList``: AND of all conditions
     - ``list/set/tuple``: OR of all conditions
     - ``numpy.void``: Like dict, from record array
@@ -398,7 +398,7 @@ def combine_conditions(negate, conditions):
     if inspect.isclass(condition) and issubclass(condition, QueryExpression):
         condition = condition()
 
-    # restrict by another expression (aka semijoin and antijoin)
+    # restrict by another expression
     if isinstance(condition, QueryExpression):
         assert_join_compatibility(query_expression, condition, semantic_check=semantic_check)
         # Match on all non-hidden namesakes (hidden attributes excluded)

src/datajoint/expression.py

@@ -1078,7 +1078,7 @@ def make_sql(self):
                 alias=next(self.__count),
                 sorting=self.sorting_clauses(),
             )
-        # with secondary attributes, use union of left join with antijoin
+        # with secondary attributes, use union of left join with anti-restriction
         fields = self.heading.names
         sql1 = arg1.join(arg2, left=True).make_sql(fields)
         sql2 = (arg2 - arg1).proj(..., **{k: "NULL" for k in arg1.heading.secondary_attributes}).make_sql(fields)