docs(readme): fix stale claims per 2026-05-17 audit

[hummbl-dev]

Fixes stale claims surfaced by 2026-05-17 forensic audit.

Changes

• Correct v2 SDK status: active in base120/ (cli.py, engine.py, models.py, ledger.py, mcp_server.py, pyproject.toml 2.0.0.dev0), not "in development"
• Fix two wrong-org URLs: hummbl-research/* → hummbl-dev/*

🤖 Generated with Claude Code

[hummbl-dev]

Codex same-account fallback review: REQUEST_CHANGES

P2: the README now says the v2 Python SDK is active and points readers to GOVERNANCE.md for the contract authority governing that SDK, but the same README still says this repository is the authoritative reference implementation for Base120 v1.0.0, and GOVERNANCE.md says the repo is authoritative for Base120 v1.x with v1.0.x freeze constraints. That leaves operators with two conflicting authorities: active v2 SDK in pyproject.toml/base120/, but governance text scoped to v1.x/v1.0.0.

Please either update the authority statement/governance pointer to separate “v1 sealed corpus authority” from “v2 SDK active implementation,” or reframe the v2 paragraph as active scaffold under v1 governance constraints. Checks are green; this is a documentation consistency blocker.