feat: Add MySQL to PostgreSQL migration tool with JSONB transformation

Implement comprehensive migration solution with:
- Full and incremental migration modes
- JSONB schema transformation for RAWDATACOR and ELABDATADISP tables
- Native PostgreSQL partitioning (2014-2031)
- Optimized GIN indexes for JSONB queries
- Rich logging with progress tracking
- Complete benchmark system for MySQL vs PostgreSQL comparison
- CLI interface with multiple commands (setup, migrate, benchmark)
- Configuration management via .env file
- Error handling and retry logic
- Batch processing for performance (configurable batch size)

Database transformations:
- RAWDATACOR: 16 Val columns + units → single JSONB measurements
- ELABDATADISP: 25+ measurement fields → structured JSONB with categories

🤖 Generated with Claude Code

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

src/migrator/state.py

@@ -0,0 +1,105 @@
+"""Migration state management."""
+import json
+from pathlib import Path
+from datetime import datetime
+from typing import Optional, Dict, Any
+from src.utils.logger import get_logger
+
+logger = get_logger(__name__)
+
+
+class MigrationState:
+    """Manage migration state for incremental migrations."""
+
+    DEFAULT_STATE_FILE = "migration_state.json"
+
+    def __init__(self, state_file: str = DEFAULT_STATE_FILE):
+        """Initialize migration state.
+
+        Args:
+            state_file: Path to state file
+        """
+        self.state_file = Path(state_file)
+        self.state = self._load_state()
+
+    def _load_state(self) -> Dict[str, Any]:
+        """Load state from file."""
+        if self.state_file.exists():
+            try:
+                with open(self.state_file, "r") as f:
+                    return json.load(f)
+            except Exception as e:
+                logger.warning(f"Failed to load state file: {e}")
+                return {}
+        return {}
+
+    def _save_state(self) -> None:
+        """Save state to file."""
+        try:
+            with open(self.state_file, "w") as f:
+                json.dump(self.state, f, indent=2)
+        except Exception as e:
+            logger.error(f"Failed to save state file: {e}")
+            raise
+
+    def get_last_timestamp(self, table: str) -> Optional[str]:
+        """Get last migration timestamp for a table.
+
+        Args:
+            table: Table name
+
+        Returns:
+            ISO format timestamp or None if not found
+        """
+        return self.state.get(table, {}).get("last_timestamp")
+
+    def set_last_timestamp(self, table: str, timestamp: str) -> None:
+        """Set last migration timestamp for a table.
+
+        Args:
+            table: Table name
+            timestamp: ISO format timestamp
+        """
+        if table not in self.state:
+            self.state[table] = {}
+
+        self.state[table]["last_timestamp"] = timestamp
+        self.state[table]["last_updated"] = datetime.utcnow().isoformat()
+        self._save_state()
+
+    def get_migration_count(self, table: str) -> int:
+        """Get total migration count for a table.
+
+        Args:
+            table: Table name
+
+        Returns:
+            Total rows migrated
+        """
+        return self.state.get(table, {}).get("total_migrated", 0)
+
+    def increment_migration_count(self, table: str, count: int) -> None:
+        """Increment migration count for a table.
+
+        Args:
+            table: Table name
+            count: Number of rows to add
+        """
+        if table not in self.state:
+            self.state[table] = {}
+
+        current = self.state[table].get("total_migrated", 0)
+        self.state[table]["total_migrated"] = current + count
+        self._save_state()
+
+    def reset(self, table: Optional[str] = None) -> None:
+        """Reset migration state.
+
+        Args:
+            table: Table name to reset, or None to reset all
+        """
+        if table:
+            self.state[table] = {}
+        else:
+            self.state = {}
+        self._save_state()