Add MCP Prompts Support

[rocknroll17]

Summary

1. Adds MCP prompts for common repetitive database analysis questions
2. Combined redundant get_table_schema functions into single comprehensive function

Key Changes

MCP Prompts Implementation

• explain_table prompt: Provides optimized prompt for common table analysis questions
• query_tuning prompt: Provides optimized prompt for frequent SQL optimization requests
• Both prompts deliver more efficient results through structured, targeted prompting

Schema Function Consolidation

• Combined get_table_schema and get_table_schema_with_relations into single get_table_schema
• Eliminated functional redundancy since one function was subset of the other
• Unified function provides comprehensive schema analysis with optional foreign key details
• Added explain_query tool for execution plan analysis

Technical Improvements

• Updated to FastMCP 2.11.3 with proper tool registration
• Fixed tool registration: FastMCP version update requires FunctionTool.from_function() for class method registration
• Backward compatible, no breaking changes
• Cleaner API surface with reduced function duplication

Why This Matters

Eliminates repetitive prompt engineering for common database questions and reduces API complexity by consolidating overlapping functionality. FastMCP update ensures proper tool registration compatibility.