feat(leads): Phase 8 — Save action, lead list page, and nav update

Save action (CreateLeadPage):
- Validate required fields: first/last name, 10-digit phone, address, city, lead source
- On failure: Sonner error toast + auto-opens first incomplete section
- On success: Sonner success toast with name + address, redirects to /emp/fa/leads
- Desktop save bar with progress % indicator and validation error message
- Back button navigates to /emp/fa/leads instead of browser history

Leads List page (LeadsListPage.jsx):
- Route: /emp/fa/leads (FIELD_AGENT, ADMIN, OWNER)
- Lead cards: name, urgency + status badges, address, phone, lead source, time ago, creator
- Search bar: filters by name, address, city, source, status
- Empty state with CTA when no leads saved yet
- Animated card entrance with staggered spring transitions

mockStore:
- Add leads[] state and addLead() action — prepends new lead with id, createdAt, status: New

Navigation:
- Sidebar "New Lead" replaced with "Leads" (ClipboardList icon) for all roles
- New Lead button lives on the list page header

Author: Satyam Rastogi

src/data/mockStore.jsx

@@ -2735,6 +2735,7 @@ export const MockStoreProvider = ({ children }) => {
     const [projects, setProjects] = useState(MOCK_PROJECTS);
     const [orders, setOrders] = useState(MOCK_ORDERS);
     const [vendorInvoices, setVendorInvoices] = useState(MOCK_VENDOR_INVOICES);
+    const [leads, setLeads] = useState([]);
 
     // Initialize properties once
     useEffect(() => {
@@ -2823,6 +2824,18 @@ export const MockStoreProvider = ({ children }) => {
             orders,
             vendorInvoices,
 
+            leads,
+            addLead: (lead) => {
+                const newLead = {
+                    ...lead,
+                    id: `lead_${Date.now()}`,
+                    createdAt: new Date().toISOString(),
+                    status: 'New',
+                };
+                setLeads(prev => [newLead, ...prev]);
+                return newLead;
+            },
+
             updatePropertyStatus,
             addMeeting,
             updateUser: (updatedUser) => {