fix / correct Gateway connector import, save_pool content-type, and FastAPI redirect_slashes

[fengtality]

Summary

Three small but impactful fixes to the gateway integration layer.

1. services/unified_connector_service.py — Gateway connector instantiates wrong class

Previously: from hummingbot.connector.gateway.gateway_base import GatewayBase as Gateway

The alias made _create_trading_connector instantiate GatewayBase for every Solana/EVM network connector. GatewayBase lacks the CLMM and swap methods that live on the Gateway subclass, so all LP executor operations on Gateway networks fail with errors like:

AttributeError: 'GatewayBase' object has no attribute 'get_pool_info_by_address'
AttributeError: 'GatewayBase' object has no attribute '_clmm_add_liquidity'

Fix: import the real Gateway subclass. Its __init__ is *args, **kwargs → super().__init__(), so the existing Gateway(connector_name=..., trading_pairs=[], trading_required=True) call site is unchanged.

2. services/gateway_client.py — save_pool triggers 415 Unsupported Media Type

save_pool was the only POST in this client that didn't pass json=. Without a JSON body, aiohttp sends no Content-Type header, and Fastify on the Gateway side rejects with:

{"detail": "Failed to save pool: Unsupported Media Type: application/octet-stream"}

This broke POST /gateway/networks/{network_id}/pools/save/{pool_address} entirely (the endpoint the Swagger UI fronts directly). Fix: pass json={} so aiohttp sets Content-Type: application/json.

3. main.py — disable trailing-slash redirects

Set redirect_slashes=False on the FastAPI app. Trailing-slash variants of routes were 307-redirecting, which interferes with Mintlify-driven docs routes that need to resolve cleanly without redirect indirection.

Test plan

• Start the API and create an lp_executor against a Solana CLMM pool (e.g., Meteora) — verify the executor reaches OPENING state and successfully submits add_liquidity (previously failed with AttributeError on first control-task tick).
• POST /gateway/networks/solana-mainnet-beta/pools/save/<known-pool-address> from the Swagger UI — verify a 200 response with pool data (previously returned 400 with the octet-stream error).
• Verify trailing-slash routes (e.g., GET /accounts vs GET /accounts/) no longer 307-redirect.

🤖 Generated with Claude Code

[rapcmia]

• Test LP executor on Meteora CLMM ✅
  • Started from a live Meteora SOL-USDC CLMM pool on solana-mainnet-beta
  • Created the lp_executor successfully through POST /executors/ ok
  • Executor logs showed the open-position flow calling Gateway successfully
  • Gateway returned a transaction signature instead of failing on the first control-task tick
  • A live position was created at aRSXTycuNLZ9jVY4aynPPa447Q69Q8rpmxvgtSNshyZ
  • No AttributeError related to missing Gateway LP methods was seen in the executor logs
• Test save Solana CLMM pool ✅
  • Called POST /gateway/networks/solana-mainnet-beta/pools/save/3C5YE97HADPDxZehYq9Cis8AXr9aNyrUsczKzE1nDbW9 (TRUMP-USDC)
  • Route returned success with pool data for the Meteora TRUMP-USDC CLMM pool
  • Response included the saved pool metadata instead of the earlier unsupported media type failure
  • Gateway auto-added the TRUMP token during the save flow
• Test trailing-slash behavior
  • GET /accounts returned 404 and GET /accounts/ returned 200
  • POST /portfolio/state returned 200 and POST /portfolio/state/ returned 404
  • GET /accounts/master_account/credentials returned 200 and GET /accounts/master_account/credentials/ returned 404
  • GET /bot-orchestration/status returned 200 and GET /bot-orchestration/status/ returned 404
  • No 307 redirects were observed on these sampled routes ✅
  • GET /docker/available-images/ returned 500, which appears to be a separate existing route issue ❌
    • Created separate issue #160

[fengtality]

@rapcmia Thanks - the issue below is caused by the / at end of certain routes. I will address it later.

GET /docker/available-images/ returned 500, which appears to be a separate existing route issue ❌

• Created separate issue Docker - the route "GET /docker/available-images/" returns 500 when image_name is empty or omitted #160