Scope DeepCompile compiler state to graph and engine lifecycles

[tohtana]

DeepCompile uses several process-global PyTorch compiler mechanisms while building graph-specific state. Scheduled recompilation also replaces previously compiled graphs.

These lifetimes did not have explicit ownership boundaries.

• Forward inputs could be consumed by a different graph
• Dynamo frame IDs could collide across engines
• Cleanup could either leave graph-specific patches installed or release shared compiler state that another engine still needed

This PR gives those existing mechanisms explicit graph and engine lifecycle ownership.

Fixes:

• Keep forward inputs in a graph-local one-shot queue and InputStorage.
• Qualify compiled-backward frames with an owner token and track them per engine.
• Keep the torch.autograd.Function patch active until the last owned backward frame is released, then clear captured backward inputs.
• Reference-count the ZeRO-3 Dynamo configuration overrides across engines and restore the original values after the last owner exits.
• Limit the graph-specific AotAutograd.__init__ patch to the Inductor compilation call and restore it in finally.
• Release engine-owned compiler state during scheduled recompilation, deactivation, and destruction.

[chatgpt-codex-connector]

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