Publish shaping: batching + deadband engine above the session

[mbreissi]

The per-signal publish config (mode, batchMs, deadband) now governs publication. A pure, virtual-clock-tested shaping engine (src/shaping.rs) sits above the device session (ADP-5), so the mtconnect and sim backends are shaped identically; src/supervisor.rs drives it with one timer per instance task.

Behavior

• Unconfigured signals untouched. No policy / batchMs: 0 publishes each reading immediately, exactly as before.
• Batching. batchMs > 0 buffers GOOD readings per signal and flushes on window expiry as ONE SouthboundSignalUpdate whose samples[] carries every buffered reading in arrival order — each sample keeping its own serverTs and extras (sequence, receivedTs, …). mode: "interval" keeps only the latest reading per window.
• Quality outranks the window. A BAD/UNCERTAIN reading flushes its signal's buffer immediately, itself included.
• Deadband on entry. SAMPLE-category numerics only (compiled against the probe model by the session; the sim fallback compiles static config). Compared against the last accepted value; quality/qualityRaw changes, non-numeric/array values, and the first reading after connect/resync/resume always pass.
• Lifecycle. Pause clears open windows (the resume snapshot republishes the current truth — flushing pre-pause readings after it would publish stale data out of order); resume re-arms the deadband; repoll and the resume snapshot bypass shaping; shutdown/reconnect/link-loss flush open windows; a reload or model drift swaps the policy table atomically with the signal-set swap, flushing changed signals' windows with their old policy.
• defaults.publishMode now resolves at compile exactly like defaults.batchMs (D-L10) and scopes to selection-derived SAMPLE signals.

Observability

New MtconnectAdapterShaping family (dims: instance): published / coalesced / deadbandDropped Total+Interval pairs. A new family rather than an extension of MtconnectStream, whose agentId dimension and shared-acquisition scope cannot carry a per-instance publication fact.

Docs

configuration.md publish rows + a new "Publish shaping" section describe the real behavior; metrics.md documents the new family; messaging-interface.md documents multi-sample samples[]; schema descriptions aligned; DESIGN.md records the decisions as D-MtconnectAdapter-L11.

Validation

• cargo test: 362 passed, 0 failed (was 329 — all pre-existing tests unmodified except compile_mtconnect signature call sites).
• cargo clippy --all-targets -- -D warnings: clean.
• cargo llvm-cov --fail-under-lines 90 (CI filter): 96.74% lines; shaping.rs 99.77%.
• Live compose harness (tests/compose.mtconnect-agent.yaml, cppagent 2.7): full agent_integration suite 6/6 green, including the new live leg — three streamed values coalesced into one multi-sample update on the tiny device (EVIDENCE live shaping: buffered=[41.25, 42.25, 43.25] flushed_samples=4 (one update)).