Fix multi-word query URL encoding for Tone3000 search

Replace spaces with PostgREST wildcards in ilike filter values so
multi-word queries like 'vox ac30' produce valid URLs.

Root cause: PostgREST filter parser doesn't handle spaces URL-encoded
as '+' in query parameter values, returning 400 Bad Request.

Fix: query.replace(' ', '*') converts spaces to PostgREST wildcards
before inserting into ilike.* pattern. 'vox ac30' becomes
ilike.*vox*ac30* -> ILIKE '%vox%ac30%'.

Changes:
- src/system/tonedownload.py: fix search_models() and search_irs()
- tests/test_tonedownload.py: update test_multi_word_query assertion

tests/test_tonedownload.py

@@ -176,6 +176,17 @@ class TestFormatSize:
     def test_edge_mb(self):
         assert format_size(1024 * 1024) == "1.0 MB"
 
+    def test_string_input(self):
+        """format_size should handle string inputs (Supabase can return string)."""
+        assert format_size("500") == "0.5 KB"
+        assert format_size("2097152") == "2.0 MB"
+        assert format_size("1024") == "1.0 KB"
+
+    def test_invalid_string(self):
+        """format_size should handle unparseable string inputs."""
+        assert format_size("not-a-number") == "Unknown"
+        assert format_size("") == "Unknown"
+
 
 # ── Client initialization ──────────────────────────────────────────────
 
@@ -389,6 +400,35 @@ class TestSearchModels:
         results = await client.search_models("nonexistent_xyz123", page=0)
         assert isinstance(results, list)
 
+    @pytest.mark.asyncio
+    async def test_multi_word_query(self, client):
+        """Multi-word queries should convert spaces to wildcards."""
+        captured_params = []
+
+        async def mock_get(path, params=None):
+            if path == "models" and params and "name" in params:
+                captured_params.append(params)
+                return [SAMPLE_MODEL_ROW]
+            if path == "users":
+                return [SAMPLE_USER_ROW]
+            if path == "tones":
+                return [SAMPLE_TONE_ROW]
+            return []
+
+        client._supabase_get = mock_get
+
+        results = await client.search_models("vox ac30", page=0)
+        assert len(results) == 1
+        assert results[0].name == "Marshall JCM800"
+
+        # Verify the Supabase param has spaces replaced with wildcards
+        assert len(captured_params) >= 1
+        name_param = captured_params[0].get("name", "")
+        assert "ilike.*vox*ac30*" in name_param
+        # Should NOT contain the raw space (which PostgREST filter parser
+        # can't handle in URL query values)
+        assert "vox ac30" not in name_param
+
 
 class TestSearchIRs:
     @pytest.mark.asyncio