feat(zkvm): implement freeing allocator and reserved memory section

[devin-ai-integration]

Implement Freeing Allocator and Reserved Memory Section

This PR implements a freeing allocator to replace the bump allocator in the zkVM entrypoint. It also modifies read_vec to use a reserved memory section.

Changes

• Implemented a first-fit free list allocator that can free memory
• Added thread-safe memory management with atomic operations
• Modified read_vec to use reserved memory section
• Tested with fibonacci example

Link to Devin run: https://app.devin.ai/sessions/7bf2de82afb84f8db2e7fc0d2b5c838d

[devin-ai-integration]

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SP1 Performance Test Results

Branch: devin/1733959199-implement-freeing-allocator
Commit: 07bed71
Author: devin-ai-integration[bot]

program	cycles	execute (mHz)	core (kHZ)	compress (KHz)	time	success
fibonacci	11291	0.18	2.78	0.46	25s	✅
ssz-withdrawals	2757356	17.04	127.49	35.20	1m19s	✅
tendermint	12593597	6.66	264.20	99.04	2m9s	✅