feat!: wishlist, upload-queue privilege recognition, and search filters (#20)

Closes the last two gaps in Soulseek's list of features an alternative client
must implement to be tolerated, and adds the result filters Nicotine+ has had
all along.

Wishlist: server code 103 is sent and code 104's announced interval is kept
rather than logged and discarded, so the re-search timer runs off the schedule
the server set. `wish add|remove|list|run` plus `serve --wishlist`; wishes
persist in config.toml as a TOML array so a comma inside a query survives.
`wish run` prints search-shaped records, so it pipes into `download --stdin`.

Privilege recognition: the code-69 user list is parsed instead of counted and
dropped, and code 92 answers `whoami` as `privilege_seconds`. Uploads now go
through a queue with a slot cap (`--upload-slots`, default 2) that serves
privileged users first — the cap is what makes the ordering mean anything, so
they are one change. `PlaceInQueueRequest` (peer code 51) is answered, where it
previously had no handler at all, and a departed peer's slot is released so a
stalled peer cannot wedge uploads shut.

Search filters: `--exclude`, `--extension`, `--min-size`, `--max-size` beside
the existing `--min-bitrate` and `--free-slots`, in one flattened arg group
shared by `search`, `get` and `wish run`.

Also serialises the library e2e suite behind the same gate `cli_e2e` already
uses: the new queue tests hold peer sockets open on purpose, which starved
concurrently-spawned soulfinds and failed unrelated download tests with
`login: Timeout`.

BREAKING CHANGE: `UploadStatus` gains a `Queued(u32)` variant, so an exhaustive
match on it no longer compiles, and `cli::Commands` gains `Wish`.

soulseek-rs-lib/src/message/peer/mod.rs

@@ -1,6 +1,7 @@
 mod file_search_response;
 mod get_share_file_list;
 mod peer_init;
+mod place_in_queue_request;
 mod place_in_queue_response;
 mod queue_upload;
 mod shared_file_list;
@@ -14,6 +15,7 @@ pub use file_search_response::{
 };
 pub use get_share_file_list::GetShareFileList;
 pub use peer_init::PeerInit;
+pub use place_in_queue_request::PlaceInQueueRequest;
 pub use place_in_queue_response::PlaceInQueueResponse;
 pub use queue_upload::QueueUploadHandler;
 pub use shared_file_list::{