fix(daemon): ship the OpenRPC document inside the crate

docs/openrpc.json lived at the repository root, outside the soulseek-rs
package, so the include_str! in proto compiled from a checkout but not
from the published tarball - cargo publish failed verification and the
v13.0.0 release stopped after publishing the lib. The document moves
into the crate's own docs/, where packaging can see it; the generator
test and every link follow.

.gitattributes

@@ -1,4 +1,4 @@
 # Generated and compared byte-for-byte by `daemon::openrpc::document_is_current`,
 # which builds its expectation with `\n`. A CRLF checkout would fail that test on
 # Windows.
-docs/openrpc.json text eol=lf
+soulseek-rs/docs/openrpc.json text eol=lf