same aiohttp session reuse

[Grommash9]

Session Management Optimization

This MR implements shared session management across all client types to improve performance and resource utilization.

Key Changes

• Added shared aiohttp.ClientSession management in base AioTxClient
• Implemented connection lifecycle methods (connect(), disconnect())
• Added async context manager support (__aenter__, __aexit__)
• Added connection state validation

Performance Impact

Performance testing shows significant improvements in RPC call times:

Before optimization (individual sessions):

rpc call time: 0.22293 sec
rpc call time: 0.21867 sec
rpc call time: 0.30874 sec
rpc call time: 0.23210 sec
rpc call time: 0.27328 sec
rpc call time: 0.66176 sec
rpc call time: 0.20494 sec
rpc call time: 0.89157 sec  # Peak
Average: ~0.35 sec

After optimization (shared session):

rpc call time: 0.15466 sec
rpc call time: 0.24238 sec
rpc call time: 0.22527 sec
rpc call time: 0.17175 sec
rpc call time: 0.14439 sec
rpc call time: 0.09237 sec  # Best
rpc call time: 0.20504 sec
Average: ~0.18 sec

Key improvements:

• ~48% reduction in average response time
• More consistent performance (less variation)
• Lower peak response times
• Some requests as fast as 0.09 seconds

Usage Example

# Using with context manager (recommended)
async with AioTxClient("node_url") as client:
    result = await client.get_balance("address")

# Or manually managing connection
client = AioTxClient("node_url")
await client.connect()
try:
    result = await client.get_balance("address")
finally:
    await client.disconnect()

Breaking Changes

• All client methods now require an active connection
• Added NotConnectedError for invalid connection state
• Clients must be explicitly connected before use

Testing

• All existing tests updated to use new connection lifecycle
• Added new test cases for connection management
• Performance tests confirm consistent improvements

Migration Guide

1. Update client instantiation to use async context manager where possible
2. Add explicit connect/disconnect calls where needed
3. Handle potential NotConnectedError exceptions
4. Review any custom client implementations to ensure they properly use shared session