v0.9.0-rc.35

Node vocabulary, Phase 3 — HierarchyLevel::Platform → HierarchyLevel::Node (ADR-068, epic #968). Converges peat-mesh on Node as the single name for the base mesh participant. Wire-breaking for the human-readable GeographicBeacon.hierarchy_level encoding ("Platform" → "Node"); numeric discriminant (Node = 0) preserved. Unblocks the peat-side rename (peat#969), whose peat-transport TAK bridge already references peat_mesh::HierarchyLevel::Node.

Changed

• BREAKING (wire): HierarchyLevel::Platform renamed to HierarchyLevel::Node (ADR-068, epic #968). Phase 3 of the peat-wide convergence on Node as the single name for the base mesh participant (eliminating the overloaded "Platform"). The base hierarchy tier is now Node; the ladder reads Node → Cell → Cohort → Federation → Coalition. Because HierarchyLevel derives Serialize/Deserialize by variant name, this changes the on-the-wire GeographicBeacon.hierarchy_level encoding from "Platform" to "Node" — a beacon emitted by a pre-rename peer no longer deserializes its base tier on a post-rename peer (and vice versa). Pre-1.0 clean break (no compatibility shim), consistent with ADR-066's own wire break. The numeric discriminant (Node = 0) is unchanged. The "platforms" document-collection name and the platform_type/node_type schema field are a separate cross-transport wire flip handled in lockstep with peat-node (epic #968 Phase 4) and are not changed here.