feat: enhance opportunity detail and sales flow

src/routes/sales/opportunity/[id]/+page.svelte

@@ -43,15 +43,50 @@
   type Tab = (typeof tabs)[number];
   let activeTab: Tab = "Overview";
 
+  // Track whether ProductsTab is in edit mode
+  let productsEditing = false;
+
+  /** Guard: block tab switch if ProductsTab has unsaved edits */
+  function guardedSetTab(tab: Tab) {
+    if (activeTab === tab) return;
+    if (productsEditing) {
+      if (!confirm('You have unsaved product changes. Discard and switch tabs?')) {
+        return;
+      }
+      productsEditing = false;
+    }
+    activeTab = tab;
+  }
+
+  // Product to auto-select when switching to Products tab
+  let pendingProductId: number | null = null;
+
+  function handleSelectProduct(e: CustomEvent<number>) {
+    pendingProductId = e.detail;
+    guardedSetTab("Products");
+  }
+
   // Mobile nav state
   let mobileActiveTab: Tab | null = null;
 
   function selectMobileTab(tab: Tab) {
+    if (productsEditing) {
+      if (!confirm('You have unsaved product changes. Discard and switch tabs?')) {
+        return;
+      }
+      productsEditing = false;
+    }
     activeTab = tab;
     mobileActiveTab = tab;
   }
 
   function mobileBack() {
+    if (productsEditing) {
+      if (!confirm('You have unsaved product changes. Discard and go back?')) {
+        return;
+      }
+      productsEditing = false;
+    }
     mobileActiveTab = null;
   }
 </script>
@@ -199,7 +234,7 @@
           class:active={activeTab === tab}
           role="tab"
           aria-selected={activeTab === tab}
-          on:click={() => (activeTab = tab)}
+          on:click={() => guardedSetTab(tab)}
         >
           {tab}
           {#if tab === "Products" && products.length > 0}
@@ -216,13 +251,21 @@
     </div>
     <div class="detail-pane-body">
       {#if activeTab === "Overview"}
-        <OverviewTab {opportunity} {notes} {contacts} {products} />
+        <OverviewTab
+          {opportunity}
+          {notes}
+          {contacts}
+          {products}
+          on:selectProduct={handleSelectProduct}
+        />
       {:else if activeTab === "Products"}
         <ProductsTab
           {products}
           accessToken={data.accessToken}
           {opportunityId}
           productSequence={opportunity?.productSequence ?? null}
+          initialProductId={pendingProductId}
+          bind:isEditing={productsEditing}
         />
       {:else if activeTab === "Notes"}
         <NotesTab