feat(go/plugins): sort tools by name for stable provider output

[Anthony-Bible]

Genkit's tool registry is a Go map, so iteration order is randomized. Without sorting, two requests with identical tool sets produce different wire bytes — which breaks Anthropic's prompt cache (and prevents stable output more generally) and from what I can tell it affects other providers like openai and gemini since that's how prompt caching works. I understand we currently don't have caching in the Go SDK and it's being worked on . But I did enable caching in a local fork to verify that sorted tools for at least Anthropic does help with caching, without sorting prompt caching is basically non-existent

I haven't actually tested this with OpenAI or Gemini, but I'd expect the same problem, their caches also depend on the request looking the same byte-for-byte each turn, and random tool order would break that too. Sorting in the shared helper is cheap, so I included them. Happy to drop those call sites if you'd rather land them separately once someone verifies.

Adds a shared SortToolDefinitions helper in go/plugins/internal and wires it into toAnthropicTools plus the compat_oai, googlegenai, and ollama providers.

[gemini-code-assist]

Code Review

This pull request introduces a SortToolDefinitions utility in a new internal package to ensure stable ordering of tool definitions across various plugins, including OpenAI, Google GenAI, Anthropic, and Ollama. This stability is necessary for consistent provider-side prompt caching. The review feedback identifies potential nil pointer dereferences in several plugins because the sorting utility preserves nil entries rather than filtering them out. Additionally, suggestions were made to optimize the sorting function for small slices and to correct the terminology used in the code documentation regarding panics.