Add location filter to library search

LibraryFilter.location does a case-insensitive substring match against
the stored location (e.g. "Box 1"), mirroring the existing text filter.
Tested for substring/case-insensitivity and the empty-string no-op case.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

crates/mtgc-core/src/filters.rs

@@ -81,6 +81,10 @@ impl Catalog {
             );
             vals.push(Value::Integer(deck_id));
         }
+        if let Some(loc) = filter.location.as_ref().map(|l| l.trim()).filter(|l| !l.is_empty()) {
+            sql.push_str(" AND LOWER(lc.location) LIKE ?");
+            vals.push(Value::Text(format!("%{}%", loc.to_lowercase())));
+        }
 
         sql.push_str(" ORDER BY oc.name COLLATE NOCASE");
 
@@ -226,4 +230,39 @@ mod tests {
         }).unwrap());
         assert_eq!(in_deck, vec!["Lightning Bolt"]);
     }
+
+    #[test]
+    fn location_filter_is_case_insensitive_substring() {
+        let fx = owned_fixture();
+        let cat = &fx.catalog;
+        cat.set_location("lightning-bolt", "Box 1").unwrap();
+        cat.set_location("sol-ring", "Box 12").unwrap();
+        cat.set_location("serra-angel", "Binder A").unwrap();
+        // llanowar-elves and deathrite-shaman are left with no location.
+
+        let box_matches = names(&cat.search_library(&LibraryFilter {
+            location: Some("box".into()),
+            ..Default::default()
+        }).unwrap());
+        assert_eq!(box_matches, vec!["Lightning Bolt", "Sol Ring"]);
+
+        let exact = names(&cat.search_library(&LibraryFilter {
+            location: Some("Box 1".into()),
+            ..Default::default()
+        }).unwrap());
+        assert_eq!(exact, vec!["Lightning Bolt", "Sol Ring"]); // substring, so "Box 1" ⊆ "Box 12" too
+
+        let none = cat.search_library(&LibraryFilter {
+            location: Some("nonexistent".into()),
+            ..Default::default()
+        }).unwrap();
+        assert!(none.is_empty());
+
+        // Empty/whitespace location text is treated as "no filter".
+        let all = cat.search_library(&LibraryFilter {
+            location: Some("   ".into()),
+            ..Default::default()
+        }).unwrap();
+        assert_eq!(all.len(), 5);
+    }
 }

crates/mtgc-core/src/model.rs

@@ -181,4 +181,7 @@ pub struct LibraryFilter {
     pub keywords: Vec<String>,
     /// Restrict to cards assigned to this deck id.
     pub in_deck: Option<i64>,
+    /// Case-insensitive substring match against the card's stored location
+    /// (e.g. "Box 1"). Cards with no location set never match a non-empty value.
+    pub location: Option<String>,
 }