ollama support updates

[madebygps]

• Add Ollama devcontainer support that uses the devcontainer feature's built-in pull option for gemma4:e4b.
• Update Ollama environment samples to default to gemma4:e4b and http://localhost:11434/v1.
• Refresh English and Spanish README Ollama setup docs with devcontainer/Codespaces guidance, tested model options, endpoint selection notes, and current RAG limitations for embedding-based samples.
• Add missing tiktoken dependency for RAG examples.

[pamelafox]

LGTM thank you!