chore: retire completed-migration scaffolding, wire orphaned boundary check (#4719)

The ecstore/global-state migrations are done (backlog#815, #939, #1052 all
closed). Review of every migration-era test/gate measure found three things
actually retirable or broken — everything else is a live anti-regression
guard and stays.

Remove:
- scripts/check_metrics_migration_refs.sh — guards a migration that
  finished: rustfs_metrics:: has zero hits, the metrics crate no longer
  exists, and the script was never wired into CI or make (only reference
  was one line in config-model-boundary-adr.md, also removed).
- crates/obs init_metrics_collectors — the "backward-compatible alias kept
  during migration" the removed script was guarding. Zero callers; pure
  delegate to init_metrics_runtime.

Archive (docs/superpowers/plans/, continuing the 2026-07 convention,
with the standard archived banner):
- startup-timeline.md, scheduler-baseline.md,
  profiling-numa-capability-inventory.md,
  kms-development-defaults-inventory.md — one-shot snapshots whose only
  consumer is the already-archived migration-progress ledger (their
  same-dir links there start resolving again after the move); zero script
  pins; fed the closed backlog#660/#665 architecture-review ledger.
  Fixed the one outbound link (startup-timeline -> readiness-matrix) that
  the move would have broken — check_doc_paths.sh deliberately does not
  scan plans/, so nothing else would have caught it.

Wire (found orphaned by the same review):
- scripts/check_extension_schema_boundaries.sh guards a live contract
  crate but was never invoked anywhere. Add lint-fmt.mak target, include
  in pre-commit/pre-pr/dev-check, add ci.yml Quick Checks step (job
  already installs ripgrep), sync the CONTRIBUTING.md enumerated list,
  and harden the script against a silently-passing rg probe when src/
  is missing.

Keep (verified live, documented so the next cleanup pass does not repeat
this analysis):
- scripts/check_architecture_migration_rules.sh — added a header stating
  it is a permanent boundary guard, not retirable migration scaffolding;
  'migration' in the name is historical.
- check_migration_gate_count.sh + floor, delete-marker e2e proof, all
  pinned docs, compat-cleanup-register sync, remaining inventories
  (referenced by live docs).

Verification: all 7 guard scripts pass, actionlint clean,
cargo check --workspace (excl e2e) clean, cargo fmt --check clean.
Adversarially reviewed by two independent skeptic passes; their 7
findings (alias left behind, broken outbound link, missing banners,
wrong backlog attribution, CONTRIBUTING drift, rg exit-2 hole, missing
header rationale) are all folded in.

crates/obs/src/lib.rs

@@ -75,8 +75,8 @@ pub use metrics::schema::*;
 pub use metrics::{
     MetricsRuntimeCancellationSource, MetricsRuntimeController, MetricsRuntimeControllerSnapshot, MetricsRuntimeDesiredSnapshot,
     MetricsRuntimeDesiredState, MetricsRuntimeIntervalsSnapshot, MetricsRuntimeReconcilePlan, MetricsRuntimeServiceState,
-    MetricsRuntimeShutdownHandle, MetricsRuntimeStatusSnapshot, MetricsRuntimeWorkerMutation, init_metrics_collectors,
-    init_metrics_runtime, metrics_runtime_controller_snapshot, metrics_runtime_status_snapshot,
+    MetricsRuntimeShutdownHandle, MetricsRuntimeStatusSnapshot, MetricsRuntimeWorkerMutation, init_metrics_runtime,
+    metrics_runtime_controller_snapshot, metrics_runtime_status_snapshot,
 };
 pub use telemetry::{OtelGuard, Recorder};
 

crates/obs/src/metrics/mod.rs

@@ -27,8 +27,8 @@ pub use report::{PrometheusMetric, report_metrics};
 pub use scheduler::{
     MetricsRuntimeCancellationSource, MetricsRuntimeController, MetricsRuntimeControllerSnapshot, MetricsRuntimeDesiredSnapshot,
     MetricsRuntimeDesiredState, MetricsRuntimeIntervalsSnapshot, MetricsRuntimeReconcilePlan, MetricsRuntimeServiceState,
-    MetricsRuntimeShutdownHandle, MetricsRuntimeStatusSnapshot, MetricsRuntimeWorkerMutation, init_metrics_collectors,
-    init_metrics_runtime, metrics_runtime_controller_snapshot, metrics_runtime_status_snapshot,
+    MetricsRuntimeShutdownHandle, MetricsRuntimeStatusSnapshot, MetricsRuntimeWorkerMutation, init_metrics_runtime,
+    metrics_runtime_controller_snapshot, metrics_runtime_status_snapshot,
 };
 pub(crate) use storage_api::metrics::{
     BucketOperations, BucketOptions, ObsBucketBandwidthMonitor, ObsEcstoreResult, ObsStore, StorageAdminApi,

crates/obs/src/metrics/scheduler.rs

@@ -1494,11 +1494,6 @@ pub fn init_metrics_runtime(token: CancellationToken) {
     });
 }
 
-/// Backward-compatible alias kept during migration.
-pub fn init_metrics_collectors(token: CancellationToken) {
-    init_metrics_runtime(token);
-}
-
 fn advance_deadline(deadline: &mut Instant, interval: Duration, now: Instant) {
     if *deadline > now {
         return;