refactor(ovsm): Replace inappropriate MCP tests with executable examples

- Remove mcp_integration_tests.rs and mcp_advanced_scenarios.rs from OVSM crate
  (these required full OSVM CLI infrastructure, not just OVSM evaluator)

- Add 3 new executable example scripts:
  - mcp_basic_rpc.ovsm: Basic blockchain RPC operations
  - mcp_wallet_analysis.ovsm: Comprehensive wallet activity dashboard
  - MCP_INTEGRATION_README.md: Complete integration guide

- Examples demonstrate actual osvm-mcp usage patterns
- Properly document architecture and troubleshooting
- Maintain 366/366 OVSM tests passing

Why: MCP integration requires McpService and McpBridgeTool from main CLI.
OVSM crate tests should only test the language interpreter itself.

Author: 0xrinegade