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/plugins/metadata_extractor.rs

@@ -2,7 +2,10 @@ use async_trait::async_trait;
 use domain::{
     entities::{AssetMetadata, MetadataSource},
     errors::DomainError,
-    ports::{AssetMetadataRepository, AssetRepository, FileStoragePort, PluginExecutor},
+    ports::{
+        AssetMetadataRepository, AssetRepository, FileStoragePort, MetadataExtractorPort,
+        PluginExecutor,
+    },
     value_objects::{MetadataValue, StructuredData, SystemId},
 };
 use std::sync::Arc;
@@ -12,6 +15,7 @@ pub struct MetadataExtractorPlugin {
     asset_repo: Arc<dyn AssetRepository>,
     file_storage: Arc<dyn FileStoragePort>,
     metadata_repo: Arc<dyn AssetMetadataRepository>,
+    extractor: Arc<dyn MetadataExtractorPort>,
 }
 
 impl MetadataExtractorPlugin {
@@ -19,11 +23,13 @@ impl MetadataExtractorPlugin {
         asset_repo: Arc<dyn AssetRepository>,
         file_storage: Arc<dyn FileStoragePort>,
         metadata_repo: Arc<dyn AssetMetadataRepository>,
+        extractor: Arc<dyn MetadataExtractorPort>,
     ) -> Self {
         Self {
             asset_repo,
             file_storage,
             metadata_repo,
+            extractor,
         }
     }
 }
@@ -52,17 +58,16 @@ impl PluginExecutor for MetadataExtractorPlugin {
 
         let path = &asset.source_reference.relative_path;
         let data = self.file_storage.read_file(path).await?;
-        let file_size = data.len() as i64;
 
-        let mut extracted = StructuredData::new();
-        extracted.insert("file_size_bytes", MetadataValue::Integer(file_size));
+        let mut extracted = self.extractor.extract(&data)?;
+        extracted.insert("file_size_bytes", MetadataValue::Integer(data.len() as i64));
         extracted.insert("mime_type", MetadataValue::String(asset.mime_type.clone()));
 
         let metadata =
             AssetMetadata::new(asset_id, MetadataSource::ExifExtracted, extracted.clone());
         self.metadata_repo.save(&metadata).await?;
 
-        info!(asset_id = %asset_id, file_size, "extracted basic metadata");
+        info!(asset_id = %asset_id, tags = extracted.len(), "extracted metadata");
         Ok(extracted)
     }
 }