feat: handle SSE cache invalidation and nightly rust toolchain config

Adds a Vue watch in `ServerDrawer.vue` to trigger a manual container directory refresh when SSE cache invalidation clears `browseData`. Includes guards to prevent redundant requests during active loads and properly manages the `isLoading` state. Additionally, introduces `rust-toolchain.toml` to enforce the nightly Rust compiler across all environments, ensuring consistent builds and access to recent language improvements.

pmoaudio/src/nodes/flac_file_sink.rs

@@ -2,7 +2,7 @@ use crate::{
     nodes::{AudioError, TypedAudioNode, DEFAULT_CHANNEL_SIZE},
     pipeline::{Node, NodeLogic},
     type_constraints::TypeRequirement,
-    AudioChunk, AudioPipelineNode, AudioSegment, SyncMarker, StreamType,
+    AudioChunk, AudioPipelineNode, AudioSegment, SyncMarker,
 };
 use pmoflac::{encode_flac_stream, EncoderOptions, PcmFormat};
 use std::{