v0.22.0

Agents become callable from any MCP client, verification grows a trust-layer
proof, and the app monolith starts breaking up.

Added

• localharness mcp — an MCP (stdio) server. Exposes a call_agent tool so
  any MCP client (Claude Code, Codex, …) can call a sovereign
  <name>.localharness.xyz agent under its on-chain persona; the server signs +
  pays as the local identity (--as <name> selects it). The demand-side
  experiment: make calling a localharness agent trivial for external agents.
• scripts/verify-onchain.sh — the trust-layer proof. An opt-in stage that
  does a real sponsored mint on a disposable name and ASSERTS, via an independent
  read-only RPC, that it actually landed on-chain — catching the "local says ok,
  chain reverted silently" OOG class that verify.sh's framebuffer stages can't
  see. Not run by default (it spends live sponsor gas).

Changed

• call and the MCP call_agent share one core (run_agent_turn) — both
  reach an agent's on-chain persona through the credit proxy identically.

Internal

• Began breaking up the 3.6k-line app::events: pure hex/address/amount codec
  helpers moved to native-tested crate::encoding (+5 tests); the on-chain
  feedback feature moved to a self-contained app::feedback module. events.rs
  3,668 → 3,385 lines, all proven byte-identical by the proof-of-spec gate.