fix(snix/docs/src/TODO): drop some items

These are migrated to https://git.snix.dev/snix/snix/issues.

Change-Id: I39c901e2cc719d5a1bf957da50b6b54ea5454481
Reviewed-on: https://cl.snix.dev/c/snix/+/30255
Autosubmit: Florian Klink <flokli@flokli.de>
Reviewed-by: Ilan Joselevich <personal@ilanjoselevich.com>
Tested-by: besadii

snix/docs/src/TODO.md

@@ -195,29 +195,6 @@ This requires some more designing. Some goals:
  - Rework the URL syntax for object_store. We should support the default s3/gcs
    URLs at least.
 
-### BlobService
- - On the trait side, currently there's no way to distinguish reading a
-   known-chunk vs blob, so we might be calling `.chunks()` unnecessarily often.
-   At least for the `object_store` backend, this might be a problem, causing a
-   lot of round-trips. It also doesn't compose well - every implementation of
-   `BlobService` needs to both solve the "holding metadata about chunking info"
-   as well as "storing chunks" questions.
-   Design idea (@flokli): split these two concerns into two separate traits:
-    - a `ChunkService` dealing with retrieving individual chunks, by their
-      content digests. Chunks are small enough to keep around in contiguous
-      memory.
-    - a `BlobService` storing metadata about blobs.
-
-   Individual stores would not need to implement `BlobReader` anymore, but that
-   could be a global thing with access to the whole store composition layer,
-   which should make it easier to reuse chunks from other backends. Unclear
-   if the write path should be structured the same way. At least for some
-   backends, we want the remote end to be able to decide about chunking.
-
- - While `object_store` recently got support for `Content-Type`
-   (https://github.com/apache/arrow-rs/pull/5650), there's no support on the
-   local filesystem yet. We'd need to add support to this (through xattrs).
-
 ### PathInfoService
  - sqlite backend (different schema than the Nix one, we need the root nodes data!)