Add B20 demo documentation

docs/AGENTS.md

@@ -93,7 +93,8 @@ npx skills add base/base-skills
 |base-chain/specs/protocol/proofs:challenger,contracts,index,proposer,registrar,tee-prover,zk-prover
 |base-chain/specs/reference:configurability,glossary
 |base-chain/specs/upgrades/azul:exec-engine,node-upgrade,overview,proofs
-|base-chain/specs/upgrades/beryl:b20-playground,b20,overview
+|base-chain/specs/upgrades/beryl:b20-playground,overview
+|base-chain/specs/upgrades/beryl/b20:demos
 |base-chain/specs/upgrades/beryl/b20/specification:index
 |base-chain/specs/upgrades/beryl/b20/specification/reference:constants-and-addresses,errors-and-events-index
 |base-chain/specs/upgrades/beryl/b20/specification/reference/interfaces:IActivationRegistry,IB20,IB20Asset,IB20Factory,IB20Stablecoin,IPolicyRegistry

docs/apps/guides/accept-b20-payments.mdx

@@ -56,6 +56,6 @@ Call `publicClient.simulateContract` with the same arguments before sending. It
 
 ## Related pages
 
-- [B20 token standard](/base-chain/specs/upgrades/beryl/b20): the full interface, including memos, policies, pausing, and roles.
+- [B20 token standard](/base-chain/specs/upgrades/beryl/b20/specification): the full interface, including memos, policies, pausing, and roles.
 - [Query B20 events](https://docs.cdp.coinbase.com/data/sql-api/b20-events): index `Transfer` and `Memo` events with the CDP SQL API to reconcile payments against orders at scale.
 - [Launch a B20 token](/get-started/launch-b20-token): create your own B20 token.

docs/base-chain/specs/upgrades/beryl/b20-playground.mdx

@@ -16,7 +16,7 @@ B20 is a superset of ERC-20: every ERC-20 call works unchanged, so there's no co
 
 ## A compliance order arrives
 
-A court order targets one account. Freeze it so it can't send, then seize the balance with one call. Seizure only works on an account that is already frozen. Every other holder is untouched and the token keeps trading. See [transfer policies](/base-chain/specs/upgrades/beryl/b20#policy-integration) and [burn](/base-chain/specs/upgrades/beryl/b20#burn) in the spec.
+A court order targets one account. Freeze it so it can't send, then seize the balance with one call. Seizure only works on an account that is already frozen. Every other holder is untouched and the token keeps trading. See [transfer policies](/base-chain/specs/upgrades/beryl/b20/specification#policy-integration) and [seizure](/base-chain/specs/upgrades/beryl/b20/specification#seize) in the specification.
 
 <Visibility for="humans">
   <B20FlowDemo flow="seize" />
@@ -32,15 +32,15 @@ Your customer pays to one address. The transfer carries the invoice reference, s
 
 ## A new user approves without gas
 
-A new user shouldn't have to buy ETH first. With `permit`, they sign an approval offchain and your platform relays it. They start transacting with zero gas, and nonces stop signature replay. See [permit](/base-chain/specs/upgrades/beryl/b20#erc-2612-permit--eip-712) in the spec.
+A new user shouldn't have to buy ETH first. With `permit`, they sign an approval offchain and your platform relays it. They start transacting with zero gas, and nonces stop signature replay. See [permit](/base-chain/specs/upgrades/beryl/b20/specification#erc-2612-permit--eip-712) in the spec.
 
 <Visibility for="humans">
   <B20FlowDemo flow="permit" />
 </Visibility>
 
 ## The stock splits
 
-A 2-for-1 split is one call. Every balance doubles without a migration or a new contract. Dividends run inside a public announcement window, so the disclosure lives onchain next to the action. The token also stores identifiers like a CUSIP. See the [Asset variant](/base-chain/specs/upgrades/beryl/b20#asset) in the spec.
+A 2-for-1 split is one call. Every balance doubles without a migration or a new contract. Dividends run inside a public announcement window, so the disclosure lives onchain next to the action. The token also stores identifiers like a CUSIP. See the [Asset variant](/base-chain/specs/upgrades/beryl/b20/specification#asset) in the spec.
 
 <Visibility for="humans">
   <B20FlowDemo flow="equity" />
@@ -55,7 +55,7 @@ A 2-for-1 split is one call. Every balance doubles without a migration or a new
   <Card title="Accept B20 payments" href="/apps/guides/accept-b20-payments">
     Integration code for memo-tagged payments and B20-specific reverts.
   </Card>
-  <Card title="B20 native token standard" href="/base-chain/specs/upgrades/beryl/b20">
+  <Card title="B20 specification" href="/base-chain/specs/upgrades/beryl/b20/specification">
     Every method, event, role, and policy in the standard.
   </Card>
   <Card title="Beryl overview" href="/base-chain/specs/upgrades/beryl/overview">

docs/base-chain/specs/upgrades/beryl/b20/demos.mdx

@@ -0,0 +1,4 @@
+---
+title: "B20 Demos"
+url: "https://chain.base.org/demos/b20"
+---

docs/base-chain/specs/upgrades/beryl/b20/specification/index.mdx

@@ -9,6 +9,7 @@ This is the normative Beryl specification for B20.
 
 B20 is Base's native ERC-20-compatible token standard implemented as Rust precompiles. It adds chain-native roles, policy scopes, memos, pausing, supply caps, ERC-2612 `permit`, deterministic factory creation, and variant-specific surfaces for Asset and Stablecoin tokens.
 
+
 ## ERC-20 Compatibility
 
 B20 is a superset of ERC-20. Standard ERC-20 calls and events keep selector and behavior parity for `transfer`, `transferFrom`, `approve`, `allowance`, `balanceOf`, `totalSupply`, `name`, `symbol`, `decimals`, `Transfer`, and `Approval`.