Openrouter migration

[neavra]

Migrate AI client from Anthropic to OpenRouter + per-request model selection

Summary

• Migrate AI provider from Anthropic to OpenRouter, enabling access to any model (Claude, Gemini, Llama, etc.) through a single API
• Add per-request model selection — frontend can optionally send a model field to override the default model per message
• Update env config from ANTHROPIC_* to AI_* env vars with sensible defaults (only AI_API_KEY is required)

Changes

• internal/ai/anthropic/client.go → internal/ai/client.go — rewrite client for OpenRouter-compatible API (headers, model fallback)
• internal/config/config.go — new AIConfig with AI_API_KEY, AI_MODEL, AI_BASE_URL, etc.
• cmd/server/main.go — wire up new config fields
• internal/service/agent/types.go — add optional Model field to SendMessageRequest
• internal/service/agent/agent.go — pass req.Model into AI request (empty string falls back to configured default)
• internal/service/agent/{tools,prompt,memory}.go — update import paths from ai/anthropic → ai
• .env.example, deploy/*.yaml, README.md — updated env vars and docs

Migration

Existing deployments need to replace env vars:
ANTHROPIC_API_KEY → AI_API_KEY (OpenRouter key)
ANTHROPIC_MODEL → AI_MODEL (has default)

Tested

• Default model (no model field) → 200, uses configured default
• Model override ("model": "google/gemini-2.5-pro") → 200, routes to Gemini
• Invalid model ("model": "fakeprovider/nonsense") → 500, clear validation error

[4others]

LGTM

[webpiratt]

Should I change anthropic token value?

[neavra]

Yes, this should be the openRouter API key. Which is a different key from anthropic, it should start with sk-or.... instead of sk-ant

[webpiratt]

@realpaaao Hi, please create https://openrouter.ai/ tokens for dev and prod and share with me