feat: XvP docs (#430)

## Summary by Sourcery

Add comprehensive documentation for the XvP Settlement module under the
asset-tokenization kit, detailing its features, usage flows, lifecycle
states, and technical implementation.

Documentation:
- Add new ‘Atomic Exchange’ MDX page explaining how to create, approve,
execute, cancel, and monitor XvP settlements
- Update asset-tokenization meta.json to register the XvP Settlement
documentation page

Author: snigdha920

content/docs/application-kits/asset-tokenization/meta.json

@@ -10,6 +10,7 @@
     "asset-classes",
     "asset-manager",
     "portfolio-manager",
+    "xvp-settlement",
     "api-portal",
     "ui-customization",
     "use-cases"

content/docs/application-kits/asset-tokenization/xvp-settlement.mdx

@@ -0,0 +1,126 @@
+---
+title: "Atomic Exchange"
+description: Enable atomic asset exchanges between parties with XvP Settlement
+---
+
+import { Callout } from "fumadocs-ui/components/callout";
+
+## SettleMint XvP Settlement
+
+The XvP (Anything-versus-Payment) Settlement module enables atomic, trustless
+exchanges of digital assets between parties. This feature provides a secure
+mechanism for executing delivery-versus-payment (DvP), payment-versus-payment
+(PvP), or any asset-versus-asset exchange in a single, indivisible transaction.
+
+## What is XvP Settlement?
+
+XvP Settlement is a smart contract-based solution that ensures all parties in a
+transaction either receive their expected assets simultaneously or the
+transaction does not execute at all. This eliminates counterparty risk and
+settlement failures common in traditional exchanges.
+
+### Key benefits
+
+- **Atomic execution**: All transfers succeed or fail together, eliminating
+  partial settlement risk
+- **Trustless operation**: No need for intermediaries or escrow services
+- **Programmable settlement**: Configure expiration dates and auto-execution
+  parameters
+- **Multi-party capability**: Support for complex settlement flows involving
+  multiple assets and participants
+
+## Creating an XvP Settlement
+
+To create a new XvP Settlement, navigate to the XvP Settlement section and click
+"Create New Settlement." The creation interface allows you to configure:
+
+1. **Settlement party**: The counterparty wallet address for the exchange
+2. **Assets**: Select the assets and amounts you wish to exchange
+3. **Expiry date**: The date after which the settlement cannot be executed
+4. **Auto-execute**: Toggle to automatically execute the settlement upon final
+   approval
+
+<Callout type="info">
+  While the underlying smart contract supports complex multi-party flows, the
+  current UI implements a simplified version allowing for exchanges between two
+  parties.
+</Callout>
+
+Once configured, submit the transaction to deploy a new XvP Settlement contract.
+The newly created settlement will appear in your settlement list for monitoring.
+
+## Approving an XvP Settlement
+
+When you're involved in an XvP Settlement (either as initiator or counterparty),
+you'll need to approve it before execution. The approval process includes:
+
+1. **Review settlement details**: Verify the assets, amounts, and expiry date
+2. **Grant asset allowances**: Approve the settlement contract to transfer your
+   assets
+3. **Submit approval**: Confirm your participation in the settlement
+
+When you approve a settlement, two transactions occur:
+
+- First, you grant the XvP contract allowance to transfer the specified assets
+  from your wallet
+- Second, you mark your approval on the settlement contract itself
+
+Once all involved parties have approved the settlement, it becomes eligible for
+execution.
+
+## Executing an XvP Settlement
+
+The execution phase is where the XvP Settlement demonstrates its value. During
+execution:
+
+1. The contract verifies all required approvals are in place
+2. It checks that the settlement hasn't expired or been cancelled
+3. It atomically transfers all assets between parties in a single transaction
+
+If auto-execution is enabled during creation, the settlement will automatically
+execute when the final party approves it. In this case, the last approver pays
+the gas fees for the execution transaction.
+
+<Callout type="warning">
+  If auto-execution is disabled, the settlement requires manual execution after
+  approvals. Any wallet can execute by paying the gas fees.
+</Callout>
+
+## Cancelling an XvP Settlement
+
+Any involved party can cancel an XvP Settlement before it has been executed.
+This provides a safety mechanism if:
+
+- Settlement parameters were incorrectly configured
+- Market conditions change before settlement execution
+- One party needs to withdraw from the agreement
+- The settlement is no longer needed
+
+Once a settlement is cancelled, it cannot be reactivated or executed.
+
+## Settlement states
+
+An XvP Settlement can exist in one of several states:
+
+- **Pending**: Created but not yet fully approved by all parties
+- **Ready**: Fully approved and ready for execution
+- **Executed**: Successfully completed, with all assets transferred
+- **Expired**: Past the cutoff date and no longer executable
+- **Cancelled**: Explicitly cancelled by an involved party
+
+These states help track the lifecycle of each settlement and provide clarity on
+its current status.
+
+## Technical implementation
+
+The XvP Settlement is powered by a secure smart contract that follows best
+practices for atomic exchanges. The contract:
+
+- Utilizes OpenZeppelin's security libraries
+- Implements reentrancy protection
+- Supports meta-transactions for gasless operations
+- Includes comprehensive error handling
+- Emits events for all key actions for auditability
+
+Each settlement contract maintains its own state and manages the asset flows
+between parties, ensuring settlement integrity and security.