feat: safe deletion, album/asset delete, trash, README update

- volume-aware deletion: read-only volumes remove DB only, writable
  volumes soft-delete to trash with configurable grace period
- trash page with restore, worker purge sweep (TRASH_RETENTION_DAYS)
- album delete endpoint + sidebar trash icon
- asset delete from timeline selection toolbar
- all listing queries exclude trashed assets (deleted_at IS NULL)
- timeline ordered by EXIF capture date, date-summary endpoint
- README rewritten with features, setup, full env var table

crates/domain/src/catalog/entities.rs

@@ -27,6 +27,8 @@ pub struct Asset {
     pub is_processed: bool,
     pub owner_user_id: SystemId,
     pub created_at: DateTimeStamp,
+    pub deleted_at: Option<DateTimeStamp>,
+    pub deleted_by: Option<SystemId>,
 }
 
 impl Asset {
@@ -46,12 +48,28 @@ impl Asset {
             is_processed: false,
             owner_user_id: owner,
             created_at: DateTimeStamp::now(),
+            deleted_at: None,
+            deleted_by: None,
         }
     }
 
     pub fn mark_processed(&mut self) {
         self.is_processed = true;
     }
+
+    pub fn is_deleted(&self) -> bool {
+        self.deleted_at.is_some()
+    }
+
+    pub fn trash(&mut self, by: SystemId) {
+        self.deleted_at = Some(DateTimeStamp::now());
+        self.deleted_by = Some(by);
+    }
+
+    pub fn restore(&mut self) {
+        self.deleted_at = None;
+        self.deleted_by = None;
+    }
 }
 
 // --- AssetFilters ---

crates/domain/src/catalog/ports.rs

@@ -38,6 +38,23 @@ pub trait AssetRepository: Send + Sync {
     ) -> Result<Vec<(chrono::NaiveDate, u64)>, DomainError>;
     async fn save(&self, asset: &Asset) -> Result<(), DomainError>;
     async fn delete(&self, id: &SystemId) -> Result<(), DomainError>;
+    async fn soft_delete(
+        &self,
+        id: &SystemId,
+        deleted_by: &SystemId,
+    ) -> Result<(), DomainError>;
+    async fn restore(&self, id: &SystemId) -> Result<(), DomainError>;
+    async fn find_trashed_before(
+        &self,
+        cutoff: chrono::DateTime<chrono::Utc>,
+    ) -> Result<Vec<Asset>, DomainError>;
+    async fn count_trashed(&self, owner_id: &SystemId) -> Result<u64, DomainError>;
+    async fn find_trashed_by_owner(
+        &self,
+        owner_id: &SystemId,
+        limit: u32,
+        offset: u32,
+    ) -> Result<Vec<Asset>, DomainError>;
 }
 
 // --- AssetMetadataRepository ---