v0.50.2

Synaptic Mesh v0.50 receiver/runtime test harness consumption rehearsal.

This release adds a local, reversible harness-consumption rehearsal that treats pinned v0.49.5 receiver-facing context blocks as deterministic local test input only.

Boundary preserved: no production runtime integration, tool execution, network/resource fetch, memory/config writes, external effects, authorization/enforcement/allow/block decisions, or agent-consumed authority. The compatibility sentinel remains top-level policyDecision: null only.

Verification included local gates, two independent local reviews (A6 and B7), PR #188 CI, main release check, and exact-tag verification for v0.50.5.