The crate is the per-node metrics/logging pipe with a universal
subscriber endpoint, but "datastream" kept getting misread as a general
messaging plane. Rename crate, module paths, and public API
(`DatastreamEndpoint` → `TelemetryEndpoint`, etc.) so misuse is visible
on sight.
Renamed contracts (all in-repo producers/consumers migrated):
- env vars `MYELIN_DATASTREAM_*` → `MYELIN_TELEMETRY_*`
- artifact `datastream.ndjson` → `telemetry.ndjson`
- actor names `telemetry-publisher` / `telemetry-sink`
- wire ALPN `swactor/telemetry/0`
- `DATASTREAM_SPEC.md` → `TELEMETRY_SPEC.md`
Also fixes two latent test breaks: `process` and `iroh-driver` tests
imported `DatastreamEvent` from the crate root, which was never
re-exported; they now use the observer path `telemetry::frame::`.
Introduce a pure, level-triggered reconciler in `crates/provisioning`
that drives a declared cluster shape toward convergence over the
existing node lifecycle, replacing the edge-triggered imperative node
orchestration in `apps/myelin`.
- `reconcile`/`reconcile_node`/`observe`: pure decider and observation
folder with stable logical-node identity, per-attempt operation
identity, and deterministic retry backoff; `ClusterDriver` is the sole
writer of observed state, coalescing triggers, recording operations as
pending before dispatch, and scheduling timed requeues.
- `IdempotentEffectExecutor`: deduplicates submissions by
`(run_id, logical_node_id, attempt)` and runs provider work on the
engine-hosted blocking substrate, never blocking a reconcile pass.
- Myelin integration: `MyelinEffectBackend` bridges `ProvisionPlugin` to
the executor contract; `LocalProcessPlugin`/`LocalDockerPlugin`
provider adapters; `ProvisionedClusterGuard` pumps triggers,
observations, and due operations.
- Retire the imperative acquire/bootstrap/teardown sequencing across
`apps/myelin` orchestration, staging, observability, and provider
adapters in favor of the declarative driver.
- Move the reconciler specification to `docs/specs/archive`.
Signed-off-by: Zachery Aaron Shores-Chmielewski <zacheryasc@gmail.com>