fix(galaxy): #875 Galaxy initialize gets a 20 s budget via per-driver-type capability defaults

Gate F (#761) against the VD03 gateway: Galaxy initialize (session open +
platform seed) took 4–5 s against Tier A's 5 s Initialize timeout, so 10 of 40
restarts failed, paid a 10 s retry and left a killed gateway worker.

DriverFactoryRegistry.Register takes optional capabilityDefaults per driver
type (GetCapabilityDefaults); DriverResilienceOptionsParser layers them over the
tier table and under the per-instance ResilienceConfig; the Host wires the
registry into DriverCapabilityInvokerFactory. Galaxy registers Initialize =
20 s (no retry, breaker 2), under the actor's 30 s pessimistic bound.

Claude-Session: https://claude.ai/code/session_01GT67AD99zQQqpLCVm3p7xk

docs/DriverLifecycle.md

@@ -134,7 +134,12 @@ following this note. `DriverResilienceOptions.GetTierDefaults(tier)` supplies
 the real per-capability timeout / retry / breaker policies, resolved via
 `DriverFactoryRegistry.GetTier` and applied by `DriverCapabilityInvokerFactory`.
 Every driver runs Tier A because no factory passes a tier, so today that means
-one uniform policy set.
+one uniform policy set — except where a driver type registers **capability
+defaults** with its factory (`DriverFactoryRegistry.Register(...,
+capabilityDefaults:)`, read back by `GetCapabilityDefaults`). Those layer over
+the tier table and under any per-instance `ResilienceConfig`. Galaxy registers
+`Initialize` = 20 s (#875): its session open plus platform seed took 4–5 s
+against a real gateway, so Tier A's 5 s failed a quarter of restarts.
 
 `IDriver` **no longer carries `GetMemoryFootprint()` or
 `FlushOptionalCachesAsync()`** (Gitea **#525**). They existed to feed