fix(inventory): preserve form state across re-renders

Fixes bug where expanding an existing storage location would close
the "Add Location" form that was currently open. This happened
because renderInventory() recreated all HTML from scratch, resetting
all inline forms to hidden state.

Solution:
- Track open form states in inventoryActions module
- Restore form visibility after each re-render
- Applies to all inline forms: add location, add items (on person,
  stored, assets)

This also fixes the related issue where switching tabs would close
open forms.

Fixes: Location disappears when expanding while adding new location

src/systems/rendering/inventory.js

@@ -4,7 +4,7 @@
  */
 
 import { extensionSettings, $inventoryContainer } from '../../core/state.js';
-import { getInventoryRenderOptions } from '../interaction/inventoryActions.js';
+import { getInventoryRenderOptions, restoreFormStates } from '../interaction/inventoryActions.js';
 import { parseItems } from '../../utils/itemParser.js';
 
 // Type imports
@@ -425,6 +425,9 @@ export function updateInventoryDisplay(containerId, options = {}) {
     const inventory = extensionSettings.userStats.inventory;
     const html = generateInventoryHTML(inventory, options);
     container.innerHTML = html;
+
+    // Restore form states after re-rendering
+    restoreFormStates();
 }
 
 /**
@@ -447,6 +450,9 @@ export function renderInventory() {
     // Generate HTML and update DOM
     const html = generateInventoryHTML(inventory, options);
     $inventoryContainer.html(html);
+
+    // Restore form states after re-rendering (fixes Bug #1)
+    restoreFormStates();
 }
 
 /**