2.0.0b1 — beta: the mechanism set freezes

Zero code changes over 2.0.0a2 — the promotion is the release. Two alphas survived first-party dogfood and a real foreign-repo deployment inside 48 hours: fourteen externally-vetted mechanisms graduated-or-dormant by measured verdicts (D-077/D-078/D-079 in docs/DECISIONS.md), both field-reported defects fixed and republished within a day, the a1 wiring caveat closed by the pre-release pin, and the worldwide mcp-2.0 break hotfixed on the stable line (1.14.5) along the way.

Beta means the 2.0 mechanism set and its defaults are frozen for the 2.0.0 line. What remains before final: telemetry accrual on the armed signals (gap-conversion rate, reinforce re-derivation rate, recording coverage → the budgets re-vote) and bug fixes only.

Still a PEP 440 pre-release: install with --pre or ==2.0.0b1; plain resolves keep getting stable 1.14.5.