feat: real EXIF extraction via adapters-exif crate

- MetadataExtractorPort in domain (bytes → StructuredData)
- adapters-exif: NomExifExtractor using nom-exif, handles EXIF + TrackInfo
- Worker's MetadataExtractorPlugin delegates to port, no longer knows nom-exif
- Filters noisy binary tags (U8Array, Undefined, Unknown)

crates/worker/src/factories/plugins.rs

@@ -1,6 +1,6 @@
 use crate::plugin_registry::InMemoryPluginRegistry;
 use crate::plugins::{MetadataExtractorPlugin, NoOpPlugin, SidecarSyncPlugin};
-use domain::ports::SidecarWriterPort;
+use domain::ports::{MetadataExtractorPort, SidecarWriterPort};
 use std::sync::Arc;
 
 use super::Repos;
@@ -9,6 +9,7 @@ pub fn build_plugin_registry(
     repos: &Repos,
     file_storage: Arc<dyn domain::ports::FileStoragePort>,
     sidecar_writer: Arc<dyn SidecarWriterPort>,
+    extractor: Arc<dyn MetadataExtractorPort>,
 ) -> InMemoryPluginRegistry {
     let mut registry = InMemoryPluginRegistry::new();
 
@@ -17,6 +18,7 @@ pub fn build_plugin_registry(
         repos.asset.clone(),
         file_storage,
         repos.metadata.clone(),
+        extractor,
     )));
 
     let export_handler = Arc::new(application::sidecar::ExportSidecarHandler::new(