fix: replace blocking requests.post with aiohttp in GovernanceEthereum

[0xbyt4]

Summary

Fix critical event loop blocking bug in GovernanceEthereum input plugin. The load_rules_from_blockchain() method was using synchronous requests.post() which blocked the entire async event loop for up to 10 seconds during blockchain RPC calls.

Problem

The original implementation had two critical issues:

1. Blocking HTTP Call: Used requests.post() (synchronous) instead of aiohttp (async)
2. Blocking in __init__: Called the blocking method during initialization

# OLD CODE (BLOCKING)
def load_rules_from_blockchain(self):
    response = requests.post(self.rpc_url, json=payload, timeout=10)  # BLOCKS EVENT LOOP
    ...

def __init__(self, config):
    self.universal_rule = self.load_rules_from_blockchain()  # Called in sync __init__!

Impact: During initialization and every poll, the entire event loop would freeze for up to 10+ seconds, preventing all other coroutines (camera, ASR, GPS, etc.) from running.

Solution

• Replace requests.post with aiohttp.ClientSession for non-blocking HTTP
• Make load_rules_from_blockchain() an async method
• Defer blockchain loading from __init__ to first _poll() call
• Add specific exception handling for aiohttp.ClientError and asyncio.TimeoutError

# NEW CODE (NON-BLOCKING)
async def load_rules_from_blockchain(self) -> Optional[str]:
    async with aiohttp.ClientSession() as session:
        async with session.post(
            self.rpc_url,
            json=payload,
            timeout=aiohttp.ClientTimeout(total=10),
        ) as response:
            result = await response.json()
            ...

def __init__(self, config):
    self.universal_rule = None  # Deferred to async context

Changes

File	Change
src/inputs/plugins/ethereum_governance.py	Replace requests with aiohttp, make method async
tests/inputs/base/test_governance_ethereum.py	Update tests with async mocks, add comprehensive coverage

Non-Blocking Verification

Added tests that run concurrent tasks during HTTP calls to verify the event loop is not blocked:

@pytest.mark.asyncio
async def test_load_rules_is_non_blocking():
    # Runs a ticker task that counts ticks during HTTP call
    # If blocking: 0 ticks | If non-blocking: 3+ ticks
    await asyncio.gather(governance_call(), concurrent_ticker())
    assert ticks_during_call >= 3  # Proves non-blocking

Test Coverage

• 24 tests - All passing
• 100% code coverage

Category	Tests
Blockchain Loading	success, failure, empty result, missing key
Exception Handling	ClientError, TimeoutError, generic Exception
Non-Blocking	load_rules, _poll concurrent verification
Decode Response	valid, invalid, too short, control chars, no 0x prefix
Message Processing	raw_to_text, buffer management, formatted output

Related PR

This PR supersedes #1361 which only added tests without the blocking fix. This PR includes:

• The critical blocking bug fix
• More comprehensive tests (24 vs 17)
• Non-blocking verification tests
• Proper aiohttp mocks instead of requests mocks

Test Plan

• uv run ruff check - Passed
• uv run black --check - Passed
• uv run isort --check-only - Passed
• uv run pyright - 0 errors
• uv run pytest tests/inputs/base/test_governance_ethereum.py -v - 24 passed
• uv run pre-commit run --files - All passed