Make Arbiter a native Spotlight API integration

[tomvaillant]

Goal

Make Arbiter a native Spotlight API integration so Spotlight no longer depends on the Data Navigator CLI or Data Navigator's global/arbiter/case-studies source, while preserving the existing browse/create/report workflow and evidence safeguards.

Source evidence

• integrations/arbiter/manifest.json is currently type: cli, probes navigator data show, and declares no key.
• integrations/arbiter/integration.md and skills/arbiter/SKILL.md route every call through navigator query and configure keys with navigator keys set arbiter.
• docs/arbiter-api.md documents the direct https://arbiter.simppl.org/api/v1 contract: Bearer auth, 14 endpoints, stable error codes, credit costs, pagination, long-call and non-idempotent write safeguards, and the attributed signup URL.
• Existing run_match.py, run_themes.py, run_report.py, run_appendix.py, and run_create.py provide offline matching, rendering, and reviewed creation/report scaffolding.

Acceptance criteria

• The Arbiter manifest is a native API integration with explicit ARBITER_API_KEY configuration, optional deployment-matched ARBITER_API_BASE, direct OpenAPI smoke/preflight behavior, and no Navigator CLI probe.
• The agent-facing integration contract uses direct HTTPS requests with file-backed JSON inputs/outputs, validates identifiers and request shapes, preserves raw upstream response fields, and never interpolates untrusted text into shell commands.
• The skill keeps the attributed signup URL and tells users to create their own key and place it in the local approved secret store/environment; no shared key or credential value is requested, logged, or written to case material.
• Browse, posts, entities, themes, report, post resolution, agent, usage, and reviewed create → search-plan → human review → finalize → progress flows retain their existing credit disclosures, confirmation gates, timeout/retry rules, sensitive-mode block, and evidence/provenance handling.
• Existing offline helpers and deterministic report/appendix behavior remain compatible with native Arbiter response shapes; no-Arbiter cases remain byte-identical.
• Spotlight's navigator and Arbiter docs no longer claim Arbiter or structured-data execution depends on Data Navigator; OSINT Navigator tool discovery remains separate.
• Focused contract, hostile-input, renderer, and mocked HTTP/preflight checks pass; live smoke is run only when a configured member-owned key is available.

Non-goals

• Do not create or finalize a real Arbiter case study during implementation or verification.
• Do not store or request API keys in chat, repository files, case files, or logs.
• Do not retire OSINT Navigator tool discovery, Navigator Skills, Navigator Workflows, or Spotlight's existing offline report scaffolding.