feat: real XMP sidecar adapter, replaces LogSidecarWriter stubs

- adapters-sidecar: XmpSidecarWriter using xmp_toolkit
- Writes StructuredData → XMP with EXIF/DC/XMP namespace routing
- Reads XMP back to StructuredData
- Wired into bootstrap + worker, deleted both LogSidecarWriter stubs

crates/worker/Cargo.toml

@@ -17,6 +17,7 @@ adapters-nats      = { workspace = true }
 adapters-event-transport = { workspace = true }
 adapters-exif      = { workspace = true }
 adapters-thumbnail = { workspace = true }
+adapters-sidecar   = { workspace = true }
 async-nats         = { workspace = true }
 
 futures           = { workspace = true }

crates/worker/src/main.rs

@@ -41,7 +41,8 @@ async fn main() -> anyhow::Result<()> {
     let file_storage = Arc::new(adapters_storage::LocalFileStorage::new(
         &config.storage_path,
     ));
-    let sidecar_writer: Arc<dyn domain::ports::SidecarWriterPort> = Arc::new(LogSidecarWriter);
+    let sidecar_writer: Arc<dyn domain::ports::SidecarWriterPort> =
+        Arc::new(adapters_sidecar::XmpSidecarWriter);
 
     // Publisher transport consumes a client clone; the consumer gets another.
     let pub_transport = adapters_nats::NatsTransport::new(nats_client.clone());
@@ -168,29 +169,3 @@ async fn main() -> anyhow::Result<()> {
     error!("event loop: NATS stream ended unexpectedly");
     Ok(())
 }
-
-struct LogSidecarWriter;
-
-#[async_trait::async_trait]
-impl domain::ports::SidecarWriterPort for LogSidecarWriter {
-    fn format_name(&self) -> &str {
-        "log_noop"
-    }
-
-    async fn write_sidecar(
-        &self,
-        _data: &domain::value_objects::StructuredData,
-        path: &str,
-    ) -> Result<(), domain::errors::DomainError> {
-        info!(path, "sidecar write (no-op)");
-        Ok(())
-    }
-
-    async fn read_sidecar(
-        &self,
-        path: &str,
-    ) -> Result<domain::value_objects::StructuredData, domain::errors::DomainError> {
-        info!(path, "sidecar read (no-op)");
-        Ok(domain::value_objects::StructuredData::new())
-    }
-}