feat: SystemOne / TypeSafe API compatibility and multi-variant Docker image matrix

[chneau]

Summary

This PR integrates changes from the fork auenkr/docker-laya with comprehensive refactoring for dual API support, unified schemas, and a multi-variant container publishing pipeline.

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✨ Added

• SystemOne / TypeSafe API Compatibility:
  • Added POST /v1/systemone and root alias POST /systemone, fully compliant with the OpenRouter System One specification and TypeSafe SDKs.
  • Added clean, route-aligned schemas: SystemOneRequest, SystemOneResponse, SystemOneChoiceAnswer, SystemOneScoreAnswer, and SystemOneNoulAnswer.
  • Added flexible model resolution supporting laya-english, english, typesafe/*, laya/*, jev-1.13, etc.
  • Generates standard response metadata (id, provider: "Laya", usage).
• Multi-Variant Matrix Publishing (CI):
  • Updated .github/workflows/publish.yml to build and publish multi-arch (linux/amd64 and linux/arm64) images across multiple tags:
    • :latest / :vX.Y.Z (Slim, ~300 MB, dynamic model download on startup)
    • :english / :vX.Y.Z-english (Pre-baked English model, ~1.3 GB, offline-ready)
    • :multilingual / :vX.Y.Z-multilingual (Pre-baked Multilingual model, ~1.8 GB)
    • :typed-decisions / :vX.Y.Z-typed-decisions (Pre-baked Typed-Decisions model, ~1.3 GB)
    • :all / :vX.Y.Z-all (Full bundle with all 3 models, ~3.5 GB)
• Tooling:
  • Added make build-model MODEL=<name> to Makefile for building local pre-baked images.

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🔄 Refactored & Unified

• Unified Question Schemas:
  • Extended standard ChoiceQuestion, ScoreQuestion, and NoulQuestion to support InstructionValue (str | dict | list), removing duplicate schema definitions.
• Dual API Support:
  • Retained all original native endpoints (/predict, /predict/bulk, /models, /presets, /detect, /email/state, /healthz) alongside /v1/systemone.
• Dockerfile Layer Caching:
  • Created /data/hf permissions before preloading under USER appuser to prevent model layer duplication while preserving online dynamic fetching for slim images.
• Documentation & OpenAPI:
  • Regenerated openapi.json covering all 8 endpoints and clean schemas.
  • Updated README.md with image tag tables, configuration options, and curl examples for both native and SystemOne endpoints.

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🗑️ Removed

• Removed hardcoded Kubernetes deployment manifest (deploy/laya-deployment.yaml).
• Removed unused _PRESET_NAMES constant in app/main.py.