feat(terminal): add directory picker before launching Claude terminal (#1752)

* Add directory picker before launching Claude terminal

* fix(terminal): preserve cwd path and strip Windows verbatim prefix

- Stop trimming non-empty paths so directories with leading/trailing
  spaces on Unix are handled correctly
- Strip \\?\ extended-length prefix from canonicalized paths on Windows
  to prevent batch script cd failures

* fix(terminal): restore UNC paths when stripping Windows verbatim prefix

Handle \\?\UNC\server\share form separately from regular \\?\ prefix,
converting it back to \\server\share so network/WSL directory paths
remain valid in batch cd commands.

* fix(terminal): use pushd for UNC paths in Windows batch launcher

`cmd.exe` cannot set a UNC path (e.g. `\\wsl$\...`) as the current
directory via `cd /d`; it errors with "CMD does not support UNC paths
as current directories". Switch to `pushd` which temporarily maps the
UNC share to a drive letter.

Rename `build_windows_cd_command` → `build_windows_cwd_command` to
reflect the broader semantics. Extract `build_windows_cwd_command_str`
and `is_windows_unc_path` helpers for testability, and add unit tests
covering drive paths, UNC paths, and batch metacharacter escaping.

Also fix minor style issues: sort mod declarations alphabetically,
add missing EOF newline in lightweight.rs, add explicit type annotation
in streaming_responses test, and reformat tray menu builder chain.

src-tauri/src/proxy/providers/streaming_responses.rs

@@ -974,7 +974,9 @@ mod tests {
             "data: {\"type\":\"response.completed\",\"response\":{\"status\":\"completed\",\"usage\":{\"input_tokens\":5,\"output_tokens\":2}}}\n\n"
         );
 
-        let upstream = stream::iter(vec![Ok(Bytes::from(input.as_bytes().to_vec()))]);
+        let upstream = stream::iter(vec![Ok::<_, std::io::Error>(Bytes::from(
+            input.as_bytes().to_vec(),
+        ))]);
         let converted = create_anthropic_sse_stream_from_responses(upstream);
         let chunks: Vec<_> = converted.collect().await;
         let events: Vec<Value> = chunks