Clean up downloaded images from daemons

**What would you like to be added**:
Introduce an automatic “cleanup” step that runs after every Syft/Stereoscope scan, deleting any image layers or temp data the providers created—so disk space never accumulates between runs.

**Why is this needed**:
Running syft scan or syft attest against images pulled from Docker or Containerd leaves those images—and their layer files—inside the local daemon. On CI runners this causes disk usage in /var/lib/docker/overlay2 (or the Containerd content store) to grow continuously, eventually filling the filesystem. Previous discussions (e.g. [stereoscope #161](https://github.com/anchore/stereoscope/pull/161), [syft #416](https://github.com/anchore/syft/issues/416)) covered temporary directories, but did not address the persistent layers created by daemon-based providers.

**Additional context**:
Patches are intended as a proof of concept: feel free to ignore them, cherry-pick pieces, or push changes directly onto the branches if there’s a cleaner way to fold this into the projects’ architecture.

**Draft Suggestion**
* https://github.com/anchore/syft/pull/3986
* https://github.com/anchore/stereoscope/pull/413

Syft patch

Area | High-level change
-- | --
Lifecycle support | Introduced a new Cleanup(ctx) method to the source.Provider interface.
Central helper | Added syft.CleanupSource() to iterate over all candidate providers and call their Cleanup.
CLI wiring | Updated getSource() to return (src, cleanupFunc, err); syft scan and syft attest now defer both src.Close() and cleanupFunc().

#### **Stereoscope patch**

| Area | High-level change |
| ------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------- |
| **Interface** | Added `Cleanup(ctx)` to `image.Provider`. |
| **Docker daemon provider** | Implemented `Cleanup` by calling Docker’s `ImageRemove` to delete the analysed image. |
| **Containerd daemon provider** | Implemented `Cleanup` via `ImageService().Delete()` to purge the image from Containerd. |
| **Other providers** (`OCI dir/tarball/registry`, `SIF`, etc.) | Implemented no-op `Cleanup` that just logs a debug message—these providers don’t leave persistent state. |
| **Common code** | Updated provider factories and helper functions so all providers now satisfy the new interface. |

Together, these two patches establish a complete create → use → cleanup lifecycle across both projects.