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.

scripts/check_architecture_migration_rules.sh

@@ -1,4 +1,12 @@
 #!/usr/bin/env bash
+#
+# Permanent architecture-boundary guard (anti-regression), NOT a
+# migration-progress gate. "migration" in the name is historical: these rules
+# were established BY the ecstore/global-state migrations (backlog#815, #939,
+# #1052 — all closed) and now keep the resulting boundaries from rotting
+# (facade bypasses, compat-shim resurrection, owner-module drift). Closed
+# migration issues are NOT a reason to retire this script or its pins.
+# Runs in ci.yml Quick Checks and .github/workflows/architecture-migration-rules.yml.
 
 set -euo pipefail
 

scripts/check_extension_schema_boundaries.sh

@@ -12,6 +12,10 @@ fail() {
 }
 
 [[ -f "$CARGO_TOML" ]] || fail "crates/extension-schema/Cargo.toml is missing"
+# Without this, a moved/removed src/ makes the rg probe below exit 2, which the
+# `if` treats as "no matches" — the check would silently pass while guarding
+# nothing.
+[[ -d "${CRATE_DIR}/src" ]] || fail "crates/extension-schema/src is missing"
 
 grep -qxF '    "crates/extension-schema", # Extension schema contracts' "${ROOT_DIR}/Cargo.toml" ||
   fail "workspace members must include crates/extension-schema"

scripts/check_metrics_migration_refs.sh

@@ -1,73 +0,0 @@
-#!/usr/bin/env bash
-
-set -euo pipefail
-
-ROOT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
-
-# Allowed references during migration bootstrap (T00 baseline).
-# Keep entries minimal and remove them as callsites are migrated.
-ALLOWLIST=(
-  "crates/obs/src/lib.rs"
-  "crates/obs/src/metrics/mod.rs"
-  "crates/obs/src/metrics/scheduler.rs"
-)
-
-is_allowed_path() {
-  local path="$1"
-  local allow
-  for allow in "${ALLOWLIST[@]}"; do
-    if [[ "$path" == "$allow" ]]; then
-      return 0
-    fi
-  done
-
-  return 1
-}
-
-MATCHES=()
-while IFS= read -r line; do
-  MATCHES+=("$line")
-done < <(
-  cd "$ROOT_DIR"
-  rg -n --no-heading \
-    -e 'rustfs_metrics::' \
-    -e '\binit_metrics_system\b' \
-    -e '\binit_metrics_collectors\b' \
-    rustfs/src crates \
-    --glob '**/*.rs' \
-    --glob '!**/tests/**' \
-    --glob '!docs/**' || true
-)
-
-while IFS= read -r line; do
-  MATCHES+=("$line")
-done < <(
-  cd "$ROOT_DIR"
-  rg -n --no-heading \
-    -e 'rustfs-metrics' \
-    -e 'crates/metrics' \
-    Cargo.toml rustfs crates \
-    --glob '**/*.toml' \
-    --glob '**/*.rs' \
-    --glob '!**/tests/**' \
-    --glob '!docs/**' || true
-)
-
-VIOLATIONS=()
-
-for hit in "${MATCHES[@]}"; do
-  file="${hit%%:*}"
-  if is_allowed_path "$file"; then
-    continue
-  fi
-
-  VIOLATIONS+=("$hit")
-done
-
-if (( ${#VIOLATIONS[@]} > 0 )); then
-  echo "Metrics migration reference guard failed: found non-allowlisted references"
-  printf '%s\n' "${VIOLATIONS[@]}"
-  exit 1
-fi
-
-echo "Metrics migration reference guard passed."