Open a scene framed, and thin out two inspector sections (#295)

Three small things asked for in one issue. A scene came up wherever
the view happened to stand, and the inspector carried a button and a
list that are better reached somewhere else.

- A scene comes up framed as if Fit had been clicked: after a
  project is loaded and when another scene is opened. From then on
  the view belongs to the user.
- An empty scene has nothing to frame and stands at the origin, one
  pixel per unit. A scene the running game loads is not framed anew.
- The Container tab is left out. It keeps the view of each container
  as before (#171).
- The Unpack button and the two lines under it are gone from the
  inspector of a placed container. Unpack container stays in the
  right-click menu of the hierarchy and of the scene view.
- The corners of a polygon collider are no row in the inspector any
  more. They are edited on the outline in the scene view. The new
  schema option noRow keeps a property out of the inspector while it
  stays a property.

Tests:
- Gate on melektaus-atx: 219 files, 3401 tests, CHECK EXIT 0.
- One new unit test in tests/core/polygon.test.ts: the corners are
  a property of the collider and no row.
- Three new e2e checks: a loaded project is framed like Fit (module
  03), an opened scene is (04), and after a real reload a click on
  Fit moves nothing (09).
- Module 09 unpacks through the right-click menu now and checks that
  the inspector offers no button.
- Full suite on melektaus-atx: 1695 checks, all pass. Smokes 24, 19
  and 21, all pass.
- No counter-probe evaluated, and nothing looked at after the build.

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

tools/e2e/09-containers.mjs

@@ -388,10 +388,12 @@ export async function containers(t) {
   const storedBeforeUnpack = (await storedObjects()).length;
   await selectObject(instanceC.id);
   check(
-    'the inspector shows what the placed container follows',
-    await has('Follows a template of 5 object(s).'),
+    'the inspector shows what the placed container follows, without a button to unpack it (#295)',
+    (await has('Follows a template of 5 object(s).')) && !(await has('Unpack')),
   );
-  await clickText('Unpack');
+  const instanceCRow = await json(`__gm.hierarchyRow(${JSON.stringify(instanceC.id)})`);
+  await click(instanceCRow.x, instanceCRow.y, 'right');
+  await clickText('Unpack container');
   check(
     'Unpack writes the content into the scene, keeping the ids and the listing',
     (await storedObjects()).length === storedBeforeUnpack + 5 &&
@@ -405,8 +407,9 @@ export async function containers(t) {
   );
   await selectObject(instanceC.id);
   check(
-    'and the inspector stops offering the unpack, there is nothing left to follow',
-    !(await has('Unpack')) && !(await has('Follows a template of 5 object(s).')),
+    'and the inspector says so, there is nothing left to follow',
+    (await has('Unpacked: its content is stored in the scene.')) &&
+      !(await has('Follows a template of 5 object(s).')),
   );
   await setTemplate(`tpl.position.x = -300`);
   check(
@@ -597,6 +600,17 @@ export async function containers(t) {
   const listedBeforeReload = (await objects()).length;
   await navigate();
   await sleep(500);
+  // The reloaded scene stands framed already (#295): a click on Fit moves nothing.
+  const afterReload = await json(`__gm.objectRect(${JSON.stringify(instanceB.id)})`);
+  const fitButton = await json(`__gm.sceneHeaderAt('fit')`);
+  await click(fitButton.x, fitButton.y);
+  const afterFit = await json(`__gm.objectRect(${JSON.stringify(instanceB.id)})`);
+  check(
+    'after a reload the scene is framed as Fit frames it',
+    Boolean(afterReload && afterFit) &&
+      ['x', 'y', 'w', 'h'].every((k) => Math.abs(afterReload[k] - afterFit[k]) < 0.01),
+    JSON.stringify({ afterReload, afterFit }),
+  );
   check(
     'a reloaded project resolves the same content again, deviations included',
     (await objects()).length === listedBeforeReload &&