SearchSpaceGroup: offer every setting of the chosen rotation set, not only on a near-exact cell

The non-reference settings of the adopted point group were offered only when the cell hosted their
rotations to within ~0.1 deg, while the reference settings - which hold the very same rotations -
were offered without asking. A cell refined free after integration a few tenths of a degree off 90
therefore lost every setting but the reference one. On an orthorhombic set whose measured screws
lie on a and c and whose b row was never recorded, that left P2(1)2(1)2(1) as the only candidate
covering both screws, and it was reported as determined. With P 21 2 21 offered, the two tie, the
b-axis screw is reported as undetermined, and the model check uses the setting the data describe.

The point-group stage still asks the cell whether a rotation set it adds is hosted; only the
setting enumeration within an already chosen set stops asking.

Validation: myob/cytc/thau x10sa p.mtz byte-identical (GPU); 7mzt fail -> unscored (b screw
undetermined, P 21 21 21 or P 21 2 21); 5cc8 unchanged; [SearchSpaceGroup] 23 cases pass incl. a
new section with a cell 0.2-0.3 deg off 90.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01K5K8jvPPbmCrbqnWkddTuB

tests/SearchSpaceGroupTest.cpp

@@ -444,6 +444,17 @@ TEST_CASE("SearchSpaceGroup names an orthorhombic screw pair on the axes it lies
         REQUIRE(result.best_space_group.has_value());
         CHECK(result.best_space_group->xhm() == "P 2 21 21");
     }
+
+    // A cell refined free after integration is a few tenths of a degree off 90. The reference
+    // candidates hold the same rotations and are offered on it, so the other settings must be too.
+    SECTION("a free cell a few tenths off 90 still offers it") {
+        opt.cell = gemmi::UnitCell(40.0, 50.0, 60.0, 90.32, 90.19, 90.19);
+        opt.enumerate_all_settings = true;
+        const auto result = SearchSpaceGroup(merged, opt);
+        INFO(SearchSpaceGroupResultToText(result));
+        REQUIRE(result.best_space_group.has_value());
+        CHECK(result.best_space_group->xhm() == "P 2 21 21");
+    }
 }
 
 // A screw on a row the sweep never recorded is not a group the data refused, it is a question