docs(contracts): update DEVELOPER_GUIDE with current architecture

Added comprehensive documentation updates to reflect the current state of the
deployment scripts architecture:

- Architecture Overview: Explains modular separation of
  infrastructure/domain/workflows
- Signer-Based API: Clarifies ethers.Signer usage and TypeChain
  integration
- Quick Start CLI: Added Hardhat and Standalone deployment modes with
  network options
- Complete Deployment Workflows: Added workflow examples for
  deploySystemWithNewBlr and deploySystemWithExistingBlr
- Resumable Deployments: Documented checkpoint-based deployment
  resumption
- Registry System: Updated with multi-registry support for custom
  facets
- Advanced Topics: Added error handling patterns, custom registry
  generation, and infrastructure extensibility
- Parameter Updates: Reflected createFundConfiguration parameter
  changes (DEFAULT_BATCH_SIZE, confirmations)

The documentation now accurately reflects:
- Registry as internal lookup mechanism (not passed as parameter)
- Signer-based API (no legacy Provider pattern)
- Full TypeChain type safety throughout
- Current facet batch deployment capabilities

Signed-off-by: Miguel_LZPF <miguel.carpena@io.builders>

Author: MiguelLZPF

.changeset/brave-docs-update.md

@@ -0,0 +1,5 @@
+---
+"@hashgraph/asset-tokenization-contracts": patch
+---
+
+Update DEVELOPER_GUIDE.md with current architecture and comprehensive script documentation including core operations, modules, and workflow patterns