Fix Balancer CoWSwap liquidity label source dependency

[tomfutago]

Thank you for contributing to Spellbook 🪄

Please open the PR in draft and mark as ready when you want to request a review.

Description:

Replace labels.balancer_cowswap_amm_pools dependencies in daily Spellbook models with chain-specific Balancer CoWSwap labels tables.

This avoids Trino analyzing the invalid stored view that references a missing hive.labels.balancer_cowswap_amm_pools_arbitrum table.

Changes included:

• Added chain-specific label sources in sources/_subprojects_outputs/dex/_sources.yml
• Updated Balancer CoWSwap AMM liquidity models (ethereum/base/arbitrum/gnosis) to read source('labels', 'balancer_cowswap_amm_pools_<chain>')
• Updated labels_addresses to union chain-specific Balancer CoWSwap labels tables directly

Validation:

• Could not run dbt compile in this cloud runtime because both pipenv and dbt are unavailable (pipenv: command not found, python3 -m dbt: No module named dbt)
• Static verification confirms all previous direct references to source('labels', 'balancer_cowswap_amm_pools') were removed from daily models

---

quick links for more information:

• README.md
• spellbook docs
• CONTRIBUTING.md

Slack Thread