consort 0.8.0 — Pi backend, any vendor through one CLI

CONSORT_BACKEND=pi drives the Pi coding agent (@earendil-works/pi-coding-agent >= 0.84.0) for any provider: Anthropic, OpenAI (API key or ChatGPT/Codex subscription OAuth), Google Vertex (ADC / service-account key) and more, behind one headless JSON-lines protocol. Attestation is native: every assistant message names its provider, model and usage (plus the server-reported model where an adapter has it); a run served by anything but the requested pair, or marked failed, is discarded. A fence extension (scripts/pi-fence.mjs) bounds Pi's tools to the workdir, mirroring Pi's own path normalisation (@, file://, ~, unicode spaces, read-path variants, symlinks incl. dangling); read-only refuses bash/edit/write; workspace-write is opt-in because Pi has no OS sandbox. anthropic as provider is refused unless the principal is stated not to be Claude. Every run is --offline; rg/fd must be resolvable up front; results are validated against the schema. Measured on a 25-file diff with 5 known defects: same gpt-5.6-sol through Pi used a third of the tokens of the Codex CLI and found the HIGH, with lower recall (2/5 vs 4/5); Gemini 3.1-pro through Pi found the HIGH that gemini-cli missed. See CHANGELOG 0.8.0 and PR #4.