v0.7.0 — Paid-API tier complete (off by default)

Completes the paid-API tier (closes #2): an off-by-default, LiteLLM-fronted last-resort tier with full operator visibility. Builds on v0.6.0's gate + adapter (C6a) with last-resort routing (C6b) and panel visibility + a runbook (C6c).

Added

• C6b — last-resort paid-API routing. The frontier-first router now falls through to a paid tier: api entry as a genuine last resort (plan §6): only after every can_orchestrate sub has failed/exhausted, and only when the api_billing_enabled gate is on. Gate off (the default) → the router never reaches a paid tier. Enabled api entries are tried in roster order; a paid success is metered tier=api/spend_avoided=0 but does not advance the rotation cursor; paid failures fail over with the same [rate-limit] annotation. Requires ≥1 orchestrator (never paid-routes a subless roster).
• C6c — paid-API visibility + runbook. The tanglebrain-gui knob panel surfaces each entry's enabled kill-switch and budget_usd_month (display-only), plus a Paid-API billing: ON/OFF banner from the global gate. New view_settings() + GET /api/settings (reads only config/settings.yaml; no key file touched). README gains a step-by-step runbook for minting a budget-scoped LiteLLM virtual key on Monad and wiring it via key_ref.

Notes

• Off by default and safe: paid billing requires the explicit api_billing_enabled gate and a per-entry enabled flag. Custody is LiteLLM-fronted (a scoped virtual key via key_ref); the hard budget cap is enforced LiteLLM-side, not by TangleBrain (v1 decision).
• 265 hermetic tests pass; each chunk passed an independent Critic review.

Full Changelog: v0.6.0...v0.7.0