refactor(api): Remove `da` API Interface from Celestia Node

### Implementation ideas

# Remove `da` Interface from Celestia Node

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## What's the Issue?
Right now, our Celestia node includes a `da` (Data Availability) interface from the Rollkit client. It was originally added to fix some dependency issues, but it's not actually part of Celestia’s official API.

## Why Remove It?
- **Extra Work:** We're maintaining something that doesn't need to be here.
- **Confusion:** Users might think `da` is a core part of the Celestia API, which it isn’t.
- **Inconsistency:** Other nodes don’t have this interface, leading to mixed expectations.

## Proposed Solution:
1. **Move the `da` Interface:**
- **Option A:** Create a separate repository for the `da` interface.
- **Option B:** Integrate it directly into the Rollkit repository.
2. **Clean Up Celestia Node:**
- Remove all `da` related code and dependencies.
- Update the documentation to point users to the new location for `da`.

## Benefits:
- **Less Maintenance:** We can focus on the core features of the Celestia node.
- **Clearer API:** Users will have a better understanding of what’s officially supported.