Reveal scope lease handles

In v1.4.4 the Go reveal-lease inheritance API takes an opaque typed handle instead of the owning statement's context.Context. Migrate callers with storage.QueryRevealScopes; there is no compatibility wrapper and no context-accepting overload of InheritQueryRevealScopes.

owner, release := storage.BeginQueryRevealScopeContext(ctx, engine, reveal)
defer release()

// Capture once, at the point that owns the leases, and keep the handle.
scopes := storage.QueryRevealScopes(owner)

// The borrowing context keeps its own cancellation, deadline and values.
nested := storage.InheritQueryRevealScopes(callerCtx, scopes)

Operation	Call
Capture the leases of an actual context	QueryRevealScopes(ctx) RevealScopes
Carry captured leases into a derived context	InheritQueryRevealScopes(ctx, scopes) context.Context
No lease	RevealScopes{} (the zero handle)

QueryRevealScopes reads leases that are already recorded on the actual caller context. Pass a real context; the call has no nil fallback, and a context without leases yields the zero handle, which inherits nothing. The handle keeps the existing lease links and no request context, so capturing it allocates nothing and cannot manufacture, refresh or replace a lease.

InheritQueryRevealScopes returns ctx unchanged when the handle holds no live lease. Otherwise it returns a derived context that keeps the caller's cancellation, deadline and values and reuses the owning lease objects. Lease identity, one lease per physical engine, active-only inheritance, release-once semantics, and database property policy and namespace resolution from the supplied projection engine are unchanged. Borrowed work must still finish before its owner releases the scope; a released lease is ignored.

Cypher is the only production caller. setRevealOnEngine captures the handle from the actual statement context when it records reveal ownership for expression-failure restoration, and bindExecutionReadScope captures it for a nested statement-valued procedure. The expression-failure slot stores the owning engine and the typed handle under its existing mutex, so it no longer retains a request context; clearRevealScope clears both. executeWithoutTransaction inherits through InheritQueryRevealScopes(ctx, scope.scopes).

No storage format, HTTP or Bolt contract changed.