Add comprehensive logging with tracing, file rotation, and systemd integration

- Add tracing-appender and tracing-journald for production logging
- Add LoggingConfig with trace_sample_rate, json_output, journald options
- Expand init_logging() with file rotation, journald, and stderr layers
- Add sanitize_path() helper for PII protection in logs
- Instrument FUSE operations with #[instrument] and trace decision points
- Instrument gRPC handlers (10 methods) with span correlation
- Add spawn instrumentation for health monitor, indexer, watcher tasks
- Add broadcast lag handling (RecvError::Lagged) in event subscribers
- Fix webhook.rs expect() calls with proper error handling
- Add logging to patterns.rs, collections.rs, artwork.rs database ops
- Add Drop impl logging for PluginManager and WatchHandle
- Update systemd service with rate limiting and journal output
- Add logrotate config and example config.toml with logging section

musicfs/dist/config.example.toml

@@ -0,0 +1,30 @@
+mount_point = "/mnt/music"
+cache_dir = "/var/cache/musicfs"
+
+[logging]
+log_dir = "/var/log/musicfs"
+json_output = true
+journald = true
+level = "musicfs=info,warn"
+trace_sample_rate = 1.0
+
+[cache]
+metadata_cache_mb = 100
+content_cache_gb = 10
+
+[health]
+check_interval_secs = 30
+timeout_ms = 5000
+unhealthy_threshold = 3
+
+[[origins]]
+id = "local"
+origin_type = "local"
+priority = 1
+path = "/srv/music"
+
+[[origins]]
+id = "nas"
+origin_type = "nfs"
+priority = 2
+mount_point = "/mnt/nas/music"

musicfs/dist/logrotate.d/musicfs

@@ -0,0 +1,9 @@
+/var/log/musicfs/*.log {
+    daily
+    rotate 30
+    compress
+    delaycompress
+    missingok
+    notifempty
+    create 0640 musicfs musicfs
+}

musicfs/dist/musicfs.service

@@ -11,10 +11,17 @@ RestartSec=5
 User=musicfs
 Group=musicfs
 
+Environment="RUST_LOG=musicfs=info,warn"
+StandardOutput=journal
+StandardError=journal
+SyslogIdentifier=musicfs
+RateLimitIntervalSec=30s
+RateLimitBurst=1000
+
 NoNewPrivileges=true
 ProtectSystem=strict
 ProtectHome=read-only
-ReadWritePaths=/var/cache/musicfs /mnt/music
+ReadWritePaths=/var/cache/musicfs /var/log/musicfs /mnt/music
 PrivateTmp=true
 
 [Install]