v3.1.0 — Pi workers + per-task effort levels

New worker integrations and a per-task reasoning-effort axis.

Added

• pi worker — the provider-agnostic pi coding CLI (Anthropic Claude spread: Haiku → Sonnet → Opus → Opus --thinking high). Headless via pi -p.
• pi-local worker — always-on local/private worker driving Ollama models through the same pi binary, for fully offline-capable runs. (Requires a configured ollama provider and a local model that emits structured tool-calls — see README.)
• Optional registry binary field so a logical worker can map to a different executable (pi-local → pi).
• Per-task effort levels — the decomposition brain assigns effort (off/low/medium/high/xhigh) per task, independent of model tier, defaulting to low. Injected per-CLI for codex/droid/pi via an effortFlags map + {{EFFORT}} slot.
• Effort-first escalation — on QA failure the attempt loop climbs effort (low → medium → high) before stepping up the model tier. Routine tasks climb effort within their tier; high-risk/complex tasks use the full effort-then-tier ladder.

Behavior change

Because effort defaults to low and is decoupled from tier, expert-tier tasks now run the expert model at low effort and escalate on QA failure — no longer pinned to high. Pin a task with effort: "high" for maximum reasoning up front.

Validation

146 tests pass; repository validation and host-skill provenance lock green. Verified with live end-to-end runs: pi worker end-to-end, effort injection (codex/pi), and effort-first escalation on both the routine and intelligent paths.