Cut provisioning round-trips: merge working+drafts, add PriorHash cac…

[attermann]

…he, embed post-op state

Every provisioning transaction over LoRa pays fixed framing + encryption

• Link overhead that dominates the actual payload. The webconsole previously needed 2-3 transactions per user action: Save = SetState + GetState refresh; Commit = Commit + GetInfo + GetState refresh; PanelOpen = GetState[working] + GetState[drafts] with a client-side diff to figure out which fields were drafted. This rework collapses each flow to a single transaction plus a cache-hit short-circuit for unchanged state.

• GET_CAPABILITIES returns a namespace map with per-ns schema hashes (was a bare id array); GET_SCHEMA gains NamespaceFilter. Enables lazy per-namespace schema loading with content-addressed caching.
• GET_STATE gains Draft (merge drafts into the working response), PriorHash (server responds { Unchanged: true } on cache hit), and Hash. Body is now { Values, Drafts?, Hash } instead of the raw ns->fields map.
• SET_STATE wraps the state map in { State, IncludeState? }; with IncludeState the response carries PostOpValues + PostOpDrafts + PostOpHash so Save refreshes in one round-trip.
• COMMIT uses a { NamespaceFilter?, IncludeState? } map (was a bare array); with IncludeState the response carries PostOpValues + PostOpHash so Commit refreshes in one round-trip.

Two latent bugs addressed: the "phantom draft from live-metric drift" that the old double-fetch pattern had to work around client-side (current_rssi and friends sampled differently between the two calls), and a Key-namespace collision (Applied=1 vs Values=1) that would have produced duplicate-key maps in the new commit response — fixed by giving post-op state distinct slots (PostOpValues=4, PostOpDrafts=5, PostOpHash=6).

Extract pack_ns_values / pack_ns_drafts helpers so op_get_state, op_set_state, and op_commit emit byte-identical Values/Drafts sub-maps — that lets SetState's PostOpHash prime the GetState PriorHash cache.

71/71 provisioning tests pass. Docs: rewrite provisioning_client_guide.md for the new wire; update provisioning_integration_guide.md (SCHEMA_VERSION=2, Void field type, schema_hash accessor); CHANGELOG gains an entry per new mechanism plus migration notes for the wire- format breaks.