feat(demo): add BUIDL-like ERC-3643 demo asset

[0xMuang]

Summary

Add a local BUIDL-like ERC-3643 demo asset profile for the Giwa MVP.

This is not real BlackRock/Securitize BUIDL integration. The demo should use the standard ERC-3643/T-REX token and express BUIDL-like behavior through Corner Store's Manifest/Recipe/Element configuration, not through bespoke token transfer logic.

Scope

• Add a BUIDL-like demo asset profile with clear metadata, e.g. name/symbol and Manifest defaults.
• Deploy a standard ERC-3643/T-REX token using that profile in the demo/test stack.
• Bind the asset to:
  • Reg D 506(c) issuance recipe
  • ICA 3(c)(7) fund recipe
  • fund applicability fact that activates Qualified Purchaser checking
• Add protected-router test coverage:
  • QP-qualified buyer succeeds
  • accredited-only/non-QP buyer is rejected before token movement
• Keep QP/compliance logic in Manifest/Recipe/Element, not in a BUIDL-specific token override.
• Update project state/docs to make clear this is a local BUIDL-like demo fixture, not the real BUIDL token.

Acceptance Criteria

• The repo has an explicit BUIDL-like demo asset profile.
• Tests deploy a standard ERC-3643/T-REX token with that profile.
• The profile's Manifest enables the 3(c)(7) fund recipe and QP requirement.
• A QP buyer can trade through ExecutionRouter.
• A non-QP buyer is rejected before any token movement.
• No code or docs imply real BlackRock/Securitize BUIDL integration.

Non-goals

• Real BUIDL integration
• Securitize whitelist/claim issuer integration
• Bridge/wrapper for actual BUIDL
• Production NAV, redemption, or dividend/yield logic
• RFQ-specific demo flow
• Full legal completeness

Suggested Tests

forge fmt --check src/demo/BuidlLikeDemoAsset.sol test/fixtures/TREXSuite.sol test/integration/IntegrationBase.sol test/integration/BUIDLLikeFlow.t.sol
forge test --offline --match-path 'test/integration/BUIDLLikeFlow.t.sol' -vv
forge test --offline