Put an uploaded original in its dated folder

The transport was built and had nowhere to aim: put_chunked has existed since
the connector landed, and the only things pushed through it are thumbnail
shards and the catalog snapshot.

The folder segments arrive already expanded, from dr_ingest::layout, rather
than being re-derived here. That split is what makes FR-NC-7a's first
consequence true — if this module worked out the folders from whatever the
local library happened to look like, two machines with differently organised
libraries would file the same photograph in two different places on one
server.

A name is resolved against one listing rather than a probe per candidate: a
day folder is one PROPFIND and the answer covers every collision in it, where
probing costs a round trip per attempt over a link that may be mobile data.
Two cameras both produce IMG_0001.CR3, and the second must not overwrite the
first.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

core/dr-sync/src/lib.rs

@@ -25,6 +25,7 @@ pub mod error;
 pub mod reachability;
 pub mod scan;
 pub mod types;
+pub mod upload;
 
 pub use capability::{Capabilities, ChangeDetection, ChunkConstraints, ServerPreviews};
 pub use error::RemoteError;
@@ -34,6 +35,7 @@ pub use types::{
     Cursor, EntryKind, Identity, Precondition, RemoteChange, RemoteEntry, RemoteId, RemotePath,
     Validator,
 };
+pub use upload::{destination, upload_original};
 
 /// TRACES: FR-NC-12
 /// A remote storage backend.