refactor: organize scripts/, remove stale root dirs, clean up structure

scripts/ reorganization:
- Sort 14 loose root scripts into subfolders:
  blockchain/ (genesis, proposer, mock chain, testnet BTC)
  dev/ (CLI wrapper, dev services, OpenAPI gen, systemd setup, domain proxy)
  ops/ (coordinator proxy, remote tunnel)
  gpu/ (miner workflow)
- Merge scripts/testing/ into scripts/test/ (eliminate duplicate folder)
- Create scripts/examples/ for usage demos and simulations

Root-level cleanup:
- Move home/ (12 simulation scripts) → scripts/examples/
- Move dev-utils/ (2 files) → scripts/dev/
- Move protocols/receipts/sample → tests/fixtures/
- Delete stale src/ (duplicate of apps/blockchain-node/src/)
- Remove empty home/, dev-utils/, protocols/ directories

Documentation updates:
- Update docs/6_architecture/8_codebase-structure.md tree and table
- Update root README.md tree to reflect new structure

README.md

@@ -48,16 +48,21 @@ aitbc/
 │   └── zk-circuits/         # ZK proof circuits (Circom)
 ├── cli/                     # CLI tools (12 command groups, 90+ subcommands)
 ├── contracts/               # Solidity smart contracts
-├── docs/                    # Documentation (structure, guides, reference, reports)
+├── docs/                    # Documentation (10 numbered sections)
 ├── extensions/              # Browser extensions (Firefox wallet)
-├── home/                    # Local simulation scripts
 ├── infra/                   # Infrastructure (nginx, k8s, helm, terraform)
 ├── packages/                # Shared libraries
 │   ├── py/aitbc-crypto/     # Cryptographic primitives
 │   ├── py/aitbc-sdk/        # Python SDK
 │   └── solidity/aitbc-token/# ERC-20 token contract
 ├── plugins/ollama/          # Ollama LLM integration
-├── scripts/                 # Deployment, GPU, service, and test scripts
+├── scripts/                 # All scripts, organized by purpose
+│   ├── blockchain/          # Genesis, proposer, mock chain
+│   ├── ci/                  # CI/CD pipeline
+│   ├── dev/                 # Dev tools, local services
+│   ├── examples/            # Usage examples and simulations
+│   ├── ops/                 # Coordinator proxy, tunnels
+│   └── test/                # Integration and verification
 ├── systemd/                 # Systemd service units
 ├── tests/                   # Test suites (unit, integration, e2e, security, CLI)
 └── website/                 # Public website and HTML documentation