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/src/output.rs

@@ -319,6 +319,9 @@ pub struct WhoamiRecord {
     pub shared_folders: u32,
     pub shared_files: u32,
     pub download_dir: String,
+    /// Seconds of privileges left on this account, or `null` when the server
+    /// did not answer in time. Zero means an ordinary account.
+    pub privilege_seconds: Option<u32>,
 }
 
 impl Record for WhoamiRecord {
@@ -405,6 +408,18 @@ impl Record for ShareStatusRecord {
     }
 }
 
+/// One standing search on the wishlist.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize)]
+pub struct WishRecord {
+    pub query: String,
+}
+
+impl Record for WishRecord {
+    fn text(&self) -> String {
+        sanitize(&self.query)
+    }
+}
+
 /// One configuration setting.
 #[derive(Debug, Clone, PartialEq, Eq, Serialize)]
 pub struct ConfigRecord {