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

docker-compose.yml

@@ -18,21 +18,10 @@ services:
       - ALPHAADVANTAGE_API_KEY=${ALPHAADVANTAGE_API_KEY}
       - JINA_API_KEY=${JINA_API_KEY}
 
-      # MCP Service Ports (fixed internally)
-      - MATH_HTTP_PORT=8000
-      - SEARCH_HTTP_PORT=8001
-      - TRADE_HTTP_PORT=8002
-      - GETPRICE_HTTP_PORT=8003
-
       # Agent Configuration
       - AGENT_MAX_STEP=${AGENT_MAX_STEP:-30}
     ports:
-      # MCP service ports (internal)
-      - "${MATH_HTTP_PORT:-8000}:8000"
-      - "${SEARCH_HTTP_PORT:-8001}:8001"
-      - "${TRADE_HTTP_PORT:-8002}:8002"
-      - "${GETPRICE_HTTP_PORT:-8003}:8003"
-      # API server port (primary interface)
+      # API server port (primary interface for external access)
       - "${API_PORT:-8080}:8080"
       # Web dashboard
       - "${WEB_HTTP_PORT:-8888}:8888"