refactor: remove unnecessary MCP service port configuration

MCP services are completely internal to the container and accessed
only via localhost. They should not be configurable or exposed.

Changes:
- Remove MATH_HTTP_PORT, SEARCH_HTTP_PORT, TRADE_HTTP_PORT,
  GETPRICE_HTTP_PORT from docker-compose.yml environment
- Remove MCP service port mappings from docker-compose.yml
- Remove MCP port configuration from .env.example
- Update README.md to remove MCP port configuration
- Update CLAUDE.md to clarify MCP services use fixed internal ports
- Update CHANGELOG.md with these simplifications

Technical details:
- MCP services hardcode to ports 8000-8003 via os.getenv() defaults
- Services only accessed via localhost URLs within container:
  - http://localhost:8000/mcp (math)
  - http://localhost:8001/mcp (search)
  - http://localhost:8002/mcp (trade)
  - http://localhost:8003/mcp (price)
- No external access needed or desired for these services
- Only API (8080) and web dashboard (8888) should be exposed

Benefits:
- Simpler configuration (4 fewer environment variables)
- Reduced attack surface (4 fewer exposed ports)
- Clearer architecture (internal vs external services)
- Prevents accidental misconfiguration of internal services

.env.example

@@ -13,14 +13,6 @@ OPENAI_API_KEY=your_openai_key_here # https://platform.openai.com/api-keys
 ALPHAADVANTAGE_API_KEY=your_alphavantage_key_here  # https://www.alphavantage.co/support/#api-key
 JINA_API_KEY=your_jina_key_here # https://jina.ai/
 
-# MCP Service Host Ports (exposed on host machine)
-# Container always uses 8000-8003 internally
-# Change these if you need different ports on your host
-MATH_HTTP_PORT=8000
-SEARCH_HTTP_PORT=8001
-TRADE_HTTP_PORT=8002
-GETPRICE_HTTP_PORT=8003
-
 # API Server Port (exposed on host machine for REST API)
 # Container ALWAYS uses port 8080 internally (hardcoded in entrypoint.sh)
 # This variable ONLY controls the host port mapping (host:API_PORT -> container:8080)