fix: Remove nest_asyncio dependency

[sddioulde]

Description

This PR removes the nest_asyncio dependency.

• nest_asyncio is unmaintained and breaks on Python 3.12+ (loop_factory parameter mismatch).
• Introduce _EvmServerAccountSync, a private class backing EvmLocalAccount that calls the three CDP signing endpoints synchronously via the existing Urllib3AuthClient. No new dependencies
• Remove nest-asyncio from pyproject.toml and regenerates lock files for python/ and examples/python/

Why not a sync-to-async bridge?

The thread-based approaches (e.g. run_coroutine_threadsafe, ThreadPoolExecutor) are patches that create new problems. The fundamental design tension would remain. The real fix is a native sync HTTP path for the subset of operations EvmLocalAccount needs.

Why not generate a second OpenAPI client?

Only 3 endpoints are needed (sign, sign/message, sign/transaction). A full generated sync client would duplicate ~250 files for no benefit. _EvmServerAccountSync is ~80 lines and entirely self-contained.

Closes #591.

Tests

Ran the example examples/python/evm/ecosystem/web3py/evm_local_account.py:

❯ uv run python evm/ecosystem/web3py/evm_local_account.py
Account:  Ethereum Account Address: 0xc689707f26756784105F54c4ED6F5Add524C560A
Account compatible with eth_account:  0xc689707f26756784105F54c4ED6F5Add524C560A

Signing hash...
Signed hash:  SignedMessage(message_hash='0x1234567890123456789012345678901234567890123456789012345678901234', r=57049031682178508804091175920335526583721405066163050094990322523056343807318, s=32387024411922934641529786598997223116757660114616745814065711894492004951358, v=27, signature=HexBytes('0x7e209b90101f84f23e648e4bba412b93af61239d599210cd776f0a638ab6f556479a67fd82fd9a123c358516eaf6c6bd997f05de9f3ff0fda9e2f98c73a7253e1b'))

Signing message...
Signed message:  SignedMessage(message_hash=b"\xb4S\xbdN'\x1e\xed\x98\\\xba\xb8#\x1d\xa6\t\xc4\xce\n\x9c\xf1\xf7c\xb6\xc1YNv1U\x10\xe0\xf1", r=37281278688649902134277016297887397123195561088545803728897652452762120801476, s=23162022271877638489387981734083191566920461287791463242810231539769917352254, v=28, signature=HexBytes('0x526c74ba2ca04d25644efc51679f9e23697d52a1dc70b4319dbf15ad1652ccc433353d72bb695184f9171a5f654b385b705a71be58898994cb2956c485f4a93e1c'))

Signing typed data with domain, types, and message...
Signed typed data for domain, types, and message:  SignedMessage(message_hash=b'L\xc0\x04*\xe2y\x04x!\x9f\xb0\x8cF\xc8\x84\xba+81I8\xad\x9f\x83\xae\xe6\nmV\x11o\xe7', r=107266443067500939413854313789399527890594981381119814998667725749699789847518, s=15453885428980507699597096617208001036297316386222485500001595931329598967832, v=28, signature=HexBytes('0xed26a7bfe224459bd1b4cca5222d1944c09db84af3234b2535038bf1c71dfbde222a96d4da183a52b0fab88c3360424dac2f9a873b0ab20289826fad3829d0181c'))

Signing typed data with full message...
Signed typed data full message:  SignedMessage(message_hash=b'L\xc0\x04*\xe2y\x04x!\x9f\xb0\x8cF\xc8\x84\xba+81I8\xad\x9f\x83\xae\xe6\nmV\x11o\xe7', r=107266443067500939413854313789399527890594981381119814998667725749699789847518, s=15453885428980507699597096617208001036297316386222485500001595931329598967832, v=28, signature=HexBytes('0xed26a7bfe224459bd1b4cca5222d1944c09db84af3234b2535038bf1c71dfbde222a96d4da183a52b0fab88c3360424dac2f9a873b0ab20289826fad3829d0181c'))

Signing typed data with bytes32 type...
Signed typed data with bytes32 type:  SignedMessage(message_hash=b'\xdc\xa4\xe9\r\xb9\xab\xc4Fyh`\xcc\xb8\xcce\xc1(\xc7\xcd\xbf)\xaca\x17&]mT\xc8\x8e\x030', r=12049388963802520052021406745481047750563729256420919116922636096368824510750, s=22071225130946302413119945222290129036807470982698496412919856288352468205610, v=28, signature=HexBytes('0x1aa3b66490cc1b5e22a26a9f7062d2e72df118a68808cafce1218cdc505b691e30cbdee816d119c982de578900b9920244f0f7f535112550c603dfee73a8002a1c'))

Signing typed data with without EIP712Domain type...
Signed typed data without EIP712Domain type:  SignedMessage(message_hash=b'l\xe5\x15o+\xa0(~\x9c\xd0\xffY\xc8\xfb\xce\x8e\xa6\xad\xdc3)\x12\x97\xfd\x14h\xda5\xc6\xb9\x05\xf1', r=21467194425975604222216938815393764240616707750017619813957818133867607634623, s=10500184178148141259044591778704833252369946689249246684299606691393129545293, v=27, signature=HexBytes('0x2f760060073f9cb74a123fb4af6e7342581ff6ad166aa2b4e9b6d16cf36c32bf1736e4c55e8f93ea4f0b26fa77e7a65ee8ea10c08b1e53e3b893cd2f8311fe4d1b'))

Signing transaction...
Signed transaction:  SignedTransaction(raw_transaction=HexBytes('0x02f87283014a340c843b9aca00843b9aca0082520894000000000000000000000000000000000000dead8502540be40080c001a0c85e3f3d2315610dc38749b1e768644e3f26556ad46ff250903792447ab998d2a07877ef1915ba857d6e69be9486bdf4ce5e075180665db83a6d988529e44c4e36'), hash=HexBytes('0x9485f3425c82dbda7b83aec485e6c1d4362a5abb874495ac7270b83891f257a3'), r=1343594100203957376813748127806706357161470955636795865396747980682439950336, s=5460044033801821160132930038842125800782084568080257075633, v=231)

Requesting ETH from faucet for account...
Received funds from faucet...
Transaction sent! Hash: 9485f3425c82dbda7b83aec485e6c1d4362a5abb874495ac7270b83891f257a3
Transaction confirmed in block 40162443
Transaction status: Success

Checklist

A couple of things to include in your PR for completeness:

• Updated the typescript README if relevant
• Updated the python README if relevant
• Added a changelog entry
• Added e2e tests if introducing new functionality

[cb-heimdall]

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