perf: cache proxy detection misses

[banteg]

Summary

• Cache proxy-detection misses in the existing proxy_info disk cache by writing JSON null for addresses confirmed not to be proxies.
• Add a proxy-info-specific cache lookup that distinguishes unchecked addresses from checked ProxyInfoAPI | None results.
• Skip ecosystem.get_proxy_info() when proxy_info/<address>.json already exists, whether it contains proxy info or null.
• Keep normal proxy-info reads returning ProxyInfoAPI | None, so a negative marker never becomes fake proxy info.
• Add backwards-compatibility coverage showing existing on-disk proxy-info JSON objects still load as proxy info.

Performance implications

This removes repeat proxy-detection work for contracts already known not to be proxies. That matters on the contract lookup hot path because a miss currently still re-enters get_proxy_info() every time when no contract type is cached.

For bytecode with no storage-backed proxy shape, the improvement is mostly CPU/cache lookup overhead. For non-proxy bytecode that contains DELEGATECALL, the null marker also avoids repeated storage probes.

Live local Reth mainnet archive-node check from the previous implementation of the same no-hit behavior:

WEB3_PROVIDER_URI=http://127.0.0.1:8545 uv run python /private/tmp/ape_proxy_miss_bench.py
provider=http://127.0.0.1:8545 chain_id=1
WETH9: before_rpc={"get_code": 0, "get_storage": 0, "send_call": 0} after_rpc={"get_code": 0, "get_storage": 0, "send_call": 0} before_mean_ms=0.381 after_mean_ms=0.032 before_median_ms=0.287 after_median_ms=0.018
Safe singleton v1.3.0: before_rpc={"get_code": 0, "get_storage": 100, "send_call": 0} after_rpc={"get_code": 0, "get_storage": 5, "send_call": 0} before_mean_ms=53.274 after_mean_ms=2.604 before_median_ms=50.451 after_median_ms=0.021

Benchmark setup used 20 repeated chain.contracts.get(..., fetch_from_explorer=False, fetch_from_disk=False) calls with ChainManager code cache pre-warmed. The "before" case clears the negative marker between calls to simulate current behavior; the "after" case keeps it.

Tests

• uv run ruff check src/ape/managers/_contractscache.py src/ape/utils/os.py tests/functional/test_contracts_cache.py
• uv run ruff format --check src/ape/managers/_contractscache.py src/ape/utils/os.py tests/functional/test_contracts_cache.py
• uv run mypy src/ape/managers/_contractscache.py src/ape/utils/os.py
• uv run pytest tests/functional/test_contracts_cache.py

Commit hook note: full-repo mypy still fails on unrelated existing errors in src/ape/cli/choices.py, src/ape/api/config.py, and src/ape_ethereum/ecosystem.py.

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