feat(snowflake-cortex): add missing but officially supported models

[davidfierro]

This PR adds officially supported models on Snowflake Cortex AI that were missing or recently published, bringing the Snowflake Cortex catalog up to date:

Models Added:

• Claude Fable 5 (claude-fable-5.toml - recently published)
• Claude Opus 4.8 (claude-opus-4-8.toml)
• OpenAI GPT-5.5 (openai-gpt-5.5.toml)
• Snowflake Llama 3.3 70B (snowflake-llama3.3-70b.toml)
• DeepSeek-R1 (deepseek-r1.toml)
• Mistral Large 2 (mistral-large2.toml)
• Gemini 3.1 Pro (gemini-3.1-pro.toml)

All configurations reuse existing global model metadata via base_model and have been validated locally using bun validate.

[rekram1-node]

are prices the exact same?

[rekram1-node]

or no prices?

[davidfierro]

@rekram1-node I haven't added prices as in Snowflake the cost depends on a concept called "credits" and the actual cost of credit is variable depending on some configurations at Snowflake level... So, no direct 1:1 translation to $