fix(task): fail closed on stale revived kernel capabilities

Retain the per-child requested-name/descriptor binding in the parent engine's
runtime capability map through SAME-host idle parking, so a cold revive in the
same live parent reaches the same closures and re-checks the original
generation/revision on every call. A host restart, a new parent kernel, a
deliberate destruction, a record expunge or parent shutdown leaves no binding:
the revived child then gets a typed tools_unavailable error stub restored ONLY
from the kernel-tool names its own transcript already recorded, and that stub
never invokes a closure. A kernel reset or a same-name redefinition yields
kernel_tool_stale on the CHILD channel and never runs a replacement closure for
an old descriptor, while a new explicit spawn resolves the new descriptor and
succeeds. Pool workers re-resolve at each new spawn and a stale tool error
produces one keyed error plus one aggregate, with no automatic retry;
process/team children stay typed unavailable. The task tool's argument
normalization now carries tools through to execute, and a refused grant reports
a typed public message instead of a generic runner failure.