feat(p2p): implement local lookup cache in batched_async_contains

[jooho-XCENA]

Summary

• Implement Tier 1 local lookup cache to skip controller round-trip for previously resolved hashes
• Update local_lookup_cache after Tier 2 controller lookup succeeds (per-hash granularity)
• Add reactive invalidation: clear stale cache entries when peer connection fails, then fall through to Tier 2

Details

batched_async_contains had two TODOs for implementing a local lookup cache. This PR:

1. Checks local_lookup_cache before hitting the controller (Tier 1), counting consecutive hashes on the same peer (prefix-match semantics matching controller logic)
2. Populates the cache after successful Tier 2 lookups
3. On peer connection failure, removes all cache entries for that peer and falls through to Tier 2

Test plan

• Verify P2P integration tests pass
• Validate Tier 1 cache hit path with repeated lookups
• Validate reactive invalidation when peer goes down

[github-actions]

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