feat(provider): add Nexus provider

[hcastc00]

What is Nexus?

Nexus is an OpenAI-compatible inference provider from Dappnode. It exposes public, private, and routed chat-completion models through the Nexus API.

• API: https://nexus-api.dappnode.com/v1
• Docs: https://nexus.dappnode.com
• Auth: NEXUS_API_KEY
• SDK: @ai-sdk/openai-compatible

Models included in this branch (12)

Adds the current chat-completion catalog exposed by Nexus:

• deepseek/deepseek-v4-flash
• deepseek/deepseek-v4-pro
• minimax/minimax-m2.7
• minimax/minmax-m3
• moonshotai/kimi-k2.6
• moonshotai/kimi-k2.7-code
• nexus/auto
• private/deepseek-v4-pro
• private/gemma4-31b
• private/glm-5.1
• private/kimi-k2.6
• zai-org/glm-5.2

Where possible, model files use canonical base_model metadata and keep only Nexus-specific pricing, limits, and capability overrides.

Sync behavior

• Adds Nexus to the shared SyncProvider registry and the aggregator sync target.
• Adds the nexus:sync package script.
• Syncs chat-completion models from GET https://nexus-api.dappnode.com/v1/models.
• Uses Nexus-provided USD pricing, context limits, output limits, base-model hints, and advertised features.
• Resolves base_model values from Nexus /v1/models to canonical metadata in models/ when possible, including bare aliases such as kimi-k2-6.

Notes

• nexus/auto is a router model, so it intentionally has no fixed per-token cost.
• Private Nexus models remain separate model IDs under private/* and use - Private display names.
• Private model canonical mappings:
  • private/deepseek-v4-pro -> deepseek/deepseek-v4-pro
  • private/gemma4-31b -> google/gemma-4-31b-it
  • private/glm-5.1 -> zhipuai/glm-5.1
  • private/kimi-k2.6 -> moonshotai/kimi-k2.6
• Nexus model IDs map directly to TOML paths under providers/nexus/models.

Structure

Follows the standard provider layout and sync-provider pattern:

• providers/nexus/provider.toml
• providers/nexus/models/**/*.toml
• providers/nexus/logo.svg
• packages/core/src/sync/providers/nexus.ts
• packages/core/src/sync/index.ts
• package.json

Verification

• git diff --check
• bun ./packages/core/script/validate.ts
• bun ./packages/core/script/sync-models.ts nexus

[rekram1-node]

AUTOMATED REVIEW: Blocking merge: the sync hardcodes unsupported reasoning controls, assumes every router supports reasoning/tools/structured output, and has already generated prices differing from its source. Derive only advertised capabilities, use audited reasoning options or [], and regenerate before merge.