Implement Week 1: Project skeleton, event models, and ingestion handlers for PyDebeziumAI

[KMohnishM]

This issue tracks the Week 1 scope for the PyDebeziumAI GSoC 2026 project.

The goal is to implement the core ingestion and data representation foundation of the Python library:

1. Ingestion handlers:
   • ConnectIngestionHandler: Reads raw Kafka Connect SourceRecord objects directly from the memory-bridge JVM context (using JPype).
   • JsonIngestionHandler: Consumes Debezium events serialized as standard JSON strings.
2. Canonical event models:
   • Normalizes different CDC structures into validated Pydantic v2 models (DebeziumEventModel and DebeziumPayloadModel).
3. Logical Type Conversion:
   • Decodes Debezium's custom formats (VariableScaleDecimals, decimals, zoned times, micro/nano durations, and geometries) into native Python types.
4. Validation:
   • Initial unit tests validating Pydantic model serialization and primary key extraction.