feat: add OrcaRouter as a named LLM provider

[JinhaoSong322]

Summary

Add OrcaRouter as a named LLM provider option for AgentTeams, mirroring the existing qwen / openai-compat named-provider wiring.

OrcaRouter is a unified AI gateway that exposes an OpenAI-compatible API at https://api.orcarouter.ai/v1. Setting AGENTTEAMS_LLM_PROVIDER=orcarouter (or credentials.llmProvider=orcarouter) routes the Manager and Workers through a single OrcaRouter API key across models. It also runs gateway-level, zero-trust security for AI agents on the same endpoint — screening every prompt/response and governing every tool call on a default-deny basis, with no application code changes.

What changed

• manager/scripts/init/setup-higress.sh — new orcarouter provider branch: registers the api.orcarouter.ai DNS service source and creates the Higress AI provider (type=openai, openaiCustomUrl=https://api.orcarouter.ai/v1), plus the default LLM_API_URL.
• manager/scripts/init/start-manager-agent.sh — same provider setup for the embedded/K8s bootstrap path.
• agentteams-controller/internal/initializer/initializer.go — new orcarouter case that registers the service source and creates the gateway provider.
• agentteams-controller/cmd/agt/llm_preflight.go — orcarouter resolves to https://api.orcarouter.ai/v1 by default in the LLM preflight probe.
• agentteams-controller/cmd/agt/llm_preflight_test.go — test asserting the orcarouter default base URL.
• install/agentteams-install.ps1 — third provider option in the interactive installer (OrcaRouter), with default model orcarouter/auto; New-OpenAICompatProvider now accepts a provider name.
• helm/agentteams/values.yaml — updated llmProvider comment.
• README.md / README.zh-CN.md / README.ja-JP.md / install/README.md — OrcaRouter usage documentation.

Verification

• go build ./cmd/agt/... ./internal/initializer/... — clean
• go test ./cmd/agt/... — pass (including new TestResolveLLMPreflightConfigDefaultsOrcaRouter)
• gofmt -l — clean on edited Go files
• bash -n — clean on both edited shell scripts
• L3 live test — a real request to https://api.orcarouter.ai/v1/chat/completions with orcarouter/auto returned HTTP 200

Disclosure: I'm an engineer on the OrcaRouter team.