feat(tvix/proto): add castore.proto r/5230

This is
0d4906cbabb183caa96e763671810fb39bd0c935:ripple/fossil/src/store.proto,
from https://src.unfathomable.blue.

It is not pulled in as a subtree, as some of the commits in there break
index-pack:

```
remote: error: object 2f487c3bf7cd8efd64f1d217edac732db98ff1c0: badDateOverflow: invalid author/committer line - date causes integer overflow
remote: fatal: fsck error in packed object
error: remote unpack failed: index-pack abnormal exit
```

Co-authored-by: edef <edef@unfathomable.blue>
Change-Id: I3369044090a3192e2322775a335887c37536a942
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7126
Tested-by: BuildkiteCI
Reviewed-by: edef <edef@edef.eu>

0 files changed, 0 insertions, 0 deletions