Read bounded trees through File handles

[SaladDay]

Environment finalization traverses and reads each package through many individual File requests. Add the declared OpenTree operation and stream its bounded, read-only result through existing Read/Release handles. Preserve both readbacks, package validation, object identity, permissions and existing installation limits. Pending acquisition and descriptor-use joins make cancellation, repeated Release and shutdown settle resources before reporting cleanup.

With the unchanged composition fixture, finalization drops from 393 to 165 RPCs. Single baseline/candidate samples at 20/100 ms per-handler delay improve from 4.797/23.621 s to 2.225/10.996 s. Go allocations decrease, but the result adds temporary memfd backing and serialization: at most four results per service, one per attachment and 128 MiB reserved backing total. No cache, fallback, setting or timeout change.

Validation: six related packages, protocol/fileservice race suites, focused race ×20, codec fuzz, vet, naming/docs/CI and translation checks passed. Nineteen privileged/native/FUSE tests require unavailable prerequisites and were skipped. The official runtime image passed local Docker memfd/sealing checks; live micro lifecycle qualification remains outstanding. Measurements do not establish peak-memory savings or closure of the live initialization failure.

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