starknet_committer: flush siblings into storage

[nimrod-starkware]

Note

Medium Risk
Touches core state-read/trie-traversal code and introduces new side effects (cache writes) during reads, which could impact correctness/perf if sibling collection is incomplete or oversized.

Overview
While building the original skeleton forest, trie traversal now collects the DB entries for unmodified sibling nodes (contracts trie, per-contract storage tries, and classes trie) and then flushes them into the storage cache via Storage::flush_to_cache.

This changes the read_forest API to take &mut Storage and updates create_contracts_trie/create_classes_trie to return sibling maps, so the read path can batch cache population after all traversals complete.

^{Written by Cursor Bugbot for commit b8e2dc7. This will update automatically on new commits. Configure here.}

[reviewable-StarkWare]

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[nimrod-starkware]

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This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
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• apollo_committer_config: validate config #12728
• starknet_committer_and_os_cli: build storage tries concurrently based on py config #12444
• starknet_patricia_storage: always cache writes in cached storage #12443
• starknet_committer: flush siblings into storage #12272 👈 (View in Graphite)
• starknet_committer: collect storage tries siblings #12271
• starknet_committer: collect siblings when traversing the tree #12270
• starknet_patricia_storage: extend the storage trait to optionally flush to cache #12269
• starknet_patricia_storage: flush explictly to cache #12267 : 1 other dependent PR (#12268 )
• starknet_committer: create storage tries based on config #12441
• starknet_committer: add a field indicating if storage tries should be created concurrently #12440
• starknet_committer: remove code dup for single trie #12201
• starknet_patricia_storage: remove code dup for mget #12175
• starknet_patricia_storage: spawn a task or not based on config #12174
• starknet_patricia_storage: add config field to rocksDB storage #12173
• starknet_patricia_storage: add config field to rocksDB #12172
• starknet_patricia_storage: spawn blocking tasks for rocksDB reads #12168 : 1 other dependent PR (#12169 )
• starknet_committer: parallel reads using unordered futures #12167
• starknet_committer: create sotrage tries sequentially #12166
• starknet_patricia,starknet_committer: dont pass storage mut when not needed #12165
• starknet_patricia_storage: non mut get in storage trait #12123 : 1 other dependent PR (#12252 )
• starknet_patricia_storage: dont cache reads in cached storage #12251
• starknet_patricia_storage: atomic counters for read stats #12122
• main-v0.14.2

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