fix(ui): floating panels stay on-screen and clear of the command dock

From gekh's review of #768, each with a test that fails before:

- P2: a floating panel whose content grows (CCTV expanded, a photo opened)
  is pulled back on-screen: every portable panel is observed and re-clamped,
  not only on window resize.
- P2: a floating header can never land under #command-dock or the voice
  pill (the rail's stacking context paints below them): clamping keeps the
  header clear of their rects on drag, restore and every re-clamp.
- A live window resize shrinks a floating window wider or taller than the
  viewport; Cyber's accordion no longer collapses docked panels when a
  floating one opens.
- The three pointer gestures share one helper (threshold, mouse/pen only,
  cancel reverts), and the header-drag threshold now has a test.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/ui/cyberPanelDisclosure.test.mjs

@@ -85,3 +85,16 @@ test('non-Cyber explicit panels and restored preferences retain their existing p
     } finally { globalThis.document = prior; }
   }
 });
+
+test('opening a floating Cyber window leaves the docked rail panels open', () => {
+  const f = fixture(), prior = globalThis.document;
+  globalThis.document = f.doc;
+  try {
+    f.owner.setPanelCollapsed('pp-toggles', false, { explicit: true });
+    f.cctv.classList.add('panel-floating');
+    f.owner.setPanelCollapsed('cctv-panel', false, { explicit: true });
+    assert.equal(f.cctv.classList.contains('collapsed'), false);
+    assert.equal(f.display.classList.contains('collapsed'), false, 'DISPLAY stays open');
+    assert.ok(!f.saved.some(([id, collapsed]) => id === 'pp-toggles' && collapsed));
+  } finally { globalThis.document = prior; }
+});