Phase 6.1 Stream B.1/B.2 — DriverTier on DriverTypeMetadata + Core.Stability.MemoryTracking with hybrid-formula soft/hard thresholds

Stream B.1 — registry invariant:
- DriverTypeMetadata gains a required `DriverTier Tier` field. Every registered
  driver type must declare its stability tier so the downstream MemoryTracking,
  MemoryRecycle, and resilience-policy layers can resolve the right defaults.
  Stamped-at-registration-time enforcement makes the "every driver type has a
  non-null Tier" compliance check structurally impossible to fail.
- DriverTypeRegistry API unchanged; one new property on the record.

Stream B.2 — MemoryTracking (Core.Stability):
- Tier-agnostic tracker per decision #146: captures baseline as the median of
  samples collected during a post-init warmup window (default 5 min), then
  classifies each subsequent sample with the hybrid formula
  `soft = max(multiplier × baseline, baseline + floor)`, `hard = 2 × soft`.
- Per-tier constants wired: Tier A mult=3 floor=50 MB, Tier B mult=3 floor=100 MB,
  Tier C mult=2 floor=500 MB.
- Never kills. Hard-breach action returns HardBreach; the supervisor that acts
  on that signal (MemoryRecycle) is Tier C only per decisions #74, #145 and
  lands in the next B.3 commit on this branch.
- Two phases: WarmingUp (samples collected, Warming returned) and Steady
  (baseline captured, soft/hard checks active). Transition is automatic when
  the warmup window elapses.

Tests (15 new, all pass):
- Warming phase returns Warming until the window elapses.
- Window-elapsed captures median baseline + transitions to Steady.
- Per-tier constants match decision #146 table exactly.
- Soft threshold uses max() — small baseline → floor wins; large baseline →
  multiplier wins.
- Hard = 2 × soft.
- Sample below soft = None; at soft = SoftBreach; at/above hard = HardBreach.
- DriverTypeRegistry: theory asserts Tier round-trips for A/B/C.

Full solution dotnet test: 963 passing (baseline 906, +57 net for Phase 6.1
Stream A + Stream B.1/B.2). Pre-existing Client.CLI Subscribe flake unchanged.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/ZB.MOM.WW.OtOpcUa.Core.Abstractions/DriverTypeRegistry.cs

@@ -69,12 +69,20 @@ public sealed class DriverTypeRegistry
 /// <param name="DriverConfigJsonSchema">JSON Schema (Draft 2020-12) the driver's <c>DriverConfig</c> column must validate against.</param>
 /// <param name="DeviceConfigJsonSchema">JSON Schema for <c>DeviceConfig</c> (multi-device drivers); null if the driver has no device layer.</param>
 /// <param name="TagConfigJsonSchema">JSON Schema for <c>TagConfig</c>; required for every driver since every driver has tags.</param>
+/// <param name="Tier">
+///     Stability tier per <c>docs/v2/driver-stability.md</c> §2-4 and <c>docs/v2/plan.md</c>
+///     decisions #63-74. Drives the shared resilience pipeline defaults
+///     (<see cref="Tier"/> × capability → <c>CapabilityPolicy</c>), the <c>MemoryTracking</c>
+///     hybrid-formula constants, and whether process-level <c>MemoryRecycle</c> / scheduled-
+///     recycle protections apply (Tier C only). Every registered driver type must declare one.
+/// </param>
 public sealed record DriverTypeMetadata(
     string TypeName,
     NamespaceKindCompatibility AllowedNamespaceKinds,
     string DriverConfigJsonSchema,
     string? DeviceConfigJsonSchema,
-    string TagConfigJsonSchema);
+    string TagConfigJsonSchema,
+    DriverTier Tier);
 
 /// <summary>Bitmask of namespace kinds a driver type may populate. Per decision #111.</summary>
 [Flags]