This PR implements Palm2/Gemini API support for EdgeChains as requested in #279.

Changes

• palm2_client.py - Python client
• palm2_types.ts - TypeScript types
• testcases/palm2/test_palm2_client.py - Unit tests
• examples/palm2_examples.jsonnet - Jsonnet examples
• lib/palm2.libsonnet - Helper library

Features

• Text generation with Gemini models
• Multi-turn chat
• Text embeddings
• Token counting
• Jsonnet-based prompts (not hardcoded)

Demo

All features implemented with comprehensive tests and examples.

/claim #279

Closes #279