Tighten rejection tests to their expected errors

Every assert.throws now names the error it expects, so a broken fixture
or an unrelated failure can no longer satisfy a rejection test. Zod
rejections are matched by issue path and code via tests/support/zod-assertions.ts.

Restore snapshot coverage lost with the release baseline: invalid board
floor, room floor and circuit section references and a reserve state
that contradicts the device rows are rejected again under test.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/project-building-structure.test.ts

@@ -253,19 +253,23 @@ describe("project building structure", () => {
       assert.equal(getFloor(context, legacyFloor.id)?.name, "EG");
 
       // A version 1 snapshot must not carry buildingId, a version 2 one must.
-      assert.throws(() =>
-        assertProjectFloorInsertProjectCommand({
-          schemaVersion: 1,
-          type: "project-floor.insert",
-          payload: { floor: { ...legacyFloor, buildingId: null } },
-        })
+      assert.throws(
+        () =>
+          assertProjectFloorInsertProjectCommand({
+            schemaVersion: 1,
+            type: "project-floor.insert",
+            payload: { floor: { ...legacyFloor, buildingId: null } },
+          }),
+        /Project-floor snapshot is invalid/
       );
-      assert.throws(() =>
-        assertProjectFloorInsertProjectCommand({
-          schemaVersion: 2,
-          type: "project-floor.insert",
-          payload: { floor: legacyFloor },
-        })
+      assert.throws(
+        () =>
+          assertProjectFloorInsertProjectCommand({
+            schemaVersion: 2,
+            type: "project-floor.insert",
+            payload: { floor: legacyFloor },
+          }),
+        /Project-floor snapshot is invalid/
       );
     } finally {
       context.close();