The deployed PDS was on v0.4.182 with a 50 MB blob upload limit, causing
upload failures for large images. Add an overlay that overrides bluesky-pds
to v0.4.219 (the latest tag in the bluesky-social/pds repo, ahead of
nixpkgs-unstable's 0.4.204) and set PDS_BLOB_UPLOAD_LIMIT explicitly to
100 MB.
Also fix `services.tangled-{knot,spindle}` -> `services.tangled.{knot,spindle}`
to match the option names exposed by the official tangled.org/@tangled.org/core
flake we import. The hyphenated names came from an older third-party flake
and have been causing every auto-update to fail since the tangled rev bumped
on Apr 20.
Anish Lakhwara