feat: add PEZ presale system with wUSDT contribution

Implemented complete presale system for PEZ token distribution:

Backend (Pallet):
- Created pallet-presale at /home/mamostehp/Pezkuwi-SDK/pezkuwi/pallets/presale/
- Accepts wUSDT (Asset ID 2) contributions
- Tracks all contributors and amounts
- Distributes PEZ (Asset ID 1) after 45-day period
- Conversion rate: 1 wUSDT = 100 PEZ
- Includes emergency pause/unpause functionality
- Runtime integration documentation provided

Frontend:
- Created Presale page with contribution form
- Live stats: time remaining, total raised, contributors count
- Real-time balance display and conversion calculator
- Progress bar showing fundraising goal ($1M target)
- Added route /presale and navigation under Trading menu
- Connected to PolkadotContext and WalletContext

Technical Details:
- wUSDT: 6 decimals (Asset ID 2)
- PEZ: 12 decimals (Asset ID 1)
- Duration: 648,000 blocks (45 days @ 6s blocks)
- Treasury: PalletId "py/prsal"

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

web/src/components/AppLayout.tsx

@@ -19,7 +19,7 @@ import { TreasuryOverview } from './treasury/TreasuryOverview';
 import { FundingProposal } from './treasury/FundingProposal';
 import { SpendingHistory } from './treasury/SpendingHistory';
 import { MultiSigApproval } from './treasury/MultiSigApproval';
-import { ExternalLink, Award, FileEdit, Users2, MessageSquare, ShieldCheck, Wifi, WifiOff, Wallet, DollarSign, PiggyBank, History, Key, TrendingUp, ArrowRightLeft, Lock, LogIn, LayoutDashboard, Settings, Users, Droplet, Mail } from 'lucide-react';
+import { ExternalLink, Award, FileEdit, Users2, MessageSquare, ShieldCheck, Wifi, WifiOff, Wallet, DollarSign, PiggyBank, History, Key, TrendingUp, ArrowRightLeft, Lock, LogIn, LayoutDashboard, Settings, Users, Droplet, Mail, Coins } from 'lucide-react';
 import GovernanceInterface from './GovernanceInterface';
 import RewardDistribution from './RewardDistribution';
 import { Tabs, TabsContent, TabsList, TabsTrigger } from '@/components/ui/tabs';
@@ -192,6 +192,13 @@ const AppLayout: React.FC = () => {
                         <Users className="w-4 h-4" />
                         P2P
                       </button>
+                      <button
+                        onClick={() => navigate('/presale')}
+                        className="w-full text-left px-4 py-2 text-gray-300 hover:bg-gray-800 hover:text-white flex items-center gap-2"
+                      >
+                        <Coins className="w-4 h-4" />
+                        Presale
+                      </button>
                       <button
                         onClick={() => setShowStaking(true)}
                         className="w-full text-left px-4 py-2 text-gray-300 hover:bg-gray-800 hover:text-white flex items-center gap-2"