feat(obs): move own values into fields and elements

`A.n = B` / `arr[i] = B` now transfer ownership: the source shadow stops owning the object (no double free) and later uses of B fail as moved. The language server marks the source moved too.

App/lib/core/Gen/AssignGenMixin.vp

@@ -1075,6 +1075,23 @@ novirtual class AssignGenMixin:
                 return (ast.Name*)(uo_b.operand).id
         return None
 
+    def _move_out_assigned_source(self, trans: HT.Translator*, rhs: ast.AST*,
+                                  pool: memhub.MemBuddy*, builder: mlirlite.IRBuilder*) -> int:
+        """OBS move: after `field = ownVar` / `arr[i] = ownVar`, the source no longer owns the value."""
+        if trans is None or rhs is None or trans.StrictOBS == 0: return 0
+        if rhs.kind() != ast.ASTKind.Name: return 0
+        src_nm: ast.Name* = ast.Name*(rhs)
+        if src_nm.id is None: return 0
+        src_slot: mlirlite.Value* = self.Gen.VarGen.lookup_var(trans.SymTab, src_nm.id)
+        if src_slot is None: return 0
+        if self.Gen.VarGen._SlifeOwned(src_slot) == 0: return 0
+        # Cancel the source's scope-exit release (the field/element now holds the pointer) and
+        # reject later uses of the moved binding.
+        ssh: mlirlite.Value* = self.Gen.VarGen._SlifeShadow(src_slot)
+        if ssh is not None: self.Gen.VarGen._SlifeNoteStore(pool, builder, ssh, 0)
+        self.Gen.VarGen._FreedMark(src_slot)
+        return 1
+
     def _is_ptr_element_annotation(self, annot: ast.AST*) -> int:
         """Return 1 if the annotation is a bytes* or str* form."""
         if annot is None: return 0
@@ -3838,6 +3855,7 @@ novirtual class AssignGenMixin:
                     vol_sw: int = 0
                     if sub_wr is not None: vol_sw = self.Gen.ExprGenAttr.base_pointee_is_volatile(pool, trans, sub_wr.value)
                     mlirlite.build_store(builder, store_val, elem_ptr, vol_sw)
+                    self._move_out_assigned_source(trans, asgn.value, pool, builder)
                     continue
                 # get_subscript_ptr returned None: try the __setitem__ overload for custom classes
                 sub_asgn: ast.Subscript* = ast.Subscript*(target)
@@ -3920,6 +3938,7 @@ novirtual class AssignGenMixin:
                                 if elem_ptr_gen is not None and elem_ptr_gen.Ty is not None:
                                     if elem_ptr_gen.Ty.Pointee != 0: store_val_gen = self.Gen.ExprGenBase.coerce_to_type(builder, rhs_val, elem_ptr_gen.Ty.Pointee, node, trans)
                                     mlirlite.build_store(builder, store_val_gen, elem_ptr_gen)
+                                    self._move_out_assigned_source(trans, asgn.value, pool, builder)
                                     setitem_done = 1
                     if setitem_done == 0: self.Gen.TypeGenErr.fatal_error(target, "subscript ptr is None")
                 continue
@@ -4018,6 +4037,7 @@ novirtual class AssignGenMixin:
                     if at_wr is not None:
                         if self.Gen.ExprGenAttr.base_pointee_is_volatile(pool, trans, at_wr.value) != 0: vol_fw = 1
                     mlirlite.build_store(builder, store_val, field_ptr, vol_fw)
+                    self._move_out_assigned_source(trans, asgn.value, pool, builder)
                     continue
                 # Guard: field_ptr is None -> build a detailed error message
                 attr_node: ast.Attribute* = ast.Attribute*(target)

App/lib/lsp/LspChecks.vp

@@ -1645,6 +1645,15 @@ def _WalkChecks(pool: memhub.MemManager*, doc: LspDocuments.LspDocument*,
                                 tn_m: ast.Name* = ast.Name*(tm)
                                 if tn_m.id is not None and _OwnHas(tn_m.id) != 0:
                                     _MovedAdd(pool, sn_a.id)
+                        # `obj.field = ownVar` / `arr[i] = ownVar`: the field/element takes ownership.
+                        ti_m2: int = 0
+                        while ti_m2 < int(len(asn.targets)):
+                            tm2: ast.AST* = asn.targets.get(sizet(ti_m2))
+                            ti_m2 += 1
+                            if tm2 is not None and (tm2.kind() == ast.ASTKind.Attribute
+                                                    or tm2.kind() == ast.ASTKind.Subscript):
+                                _MovedAdd(pool, sn_a.id)
+                                break
                 ti_c: int = 0
                 while ti_c < int(len(asn.targets)):
                     tc: ast.AST* = asn.targets.get(sizet(ti_c))