### Description
This PR introduces the **Moonwall** end-to-end (E2E) testing framework.
The primary motivation for this is to enable the porting of existing
Mobeam tests into the `DataHaven` repository.
### Key Changes
* **Node Manual Sealing:**
* Introduced a `--sealing=manual` flag for the `datahaven-node`. When
enabled, blocks are only produced on demand via an RPC call. This is the
core mechanism that allows for deterministic tests.
* **Moonwall Framework Integration:**
* Added `@moonwall/cli` and `@moonwall/util` dependencies to the
`test/package.json`.
* A new `test/moonwall.config.json` file configures the test
environment, defining how Moonwall should launch the `datahaven-node`
with the manual sealing flag.
* Added a `moonwall:test` script to `package.json` for running the
tests.
* **CI Workflow:**
* A new reusable workflow, `.github/workflows/task-moonwall-tests.yml`,
has been created to handle the setup, execution, and reporting of
Moonwall tests.
* The main `CI.yml` now includes a `moonwall-tests` job that runs after
the `build-operator` job, ensuring it always tests the correct,
freshly-built binary.
* **Example Test Suite:**
* A new test suite, `test/datahaven/suites/dev/test-block.ts`, had been
copied from moonbeam.
### How to Run Locally
1. Navigate to the `test` directory.
2. Install dependencies: `bun install`
3. Run the tests: `bun run moonwall:test`
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Co-authored-by: undercover-cactus <lola@moonsonglabs.com>
