fix(filters): support project filter in parentheses (#1647)

The filter regex pattern was not matching values inside parentheses correctly.
The lookahead pattern only allowed `&&`, `||`, or end-of-string after filter
values, but when filters are wrapped in parentheses like `( project = Filtertest )`,
the closing `)` appears after the value.

Fixed by adding `\)` to the lookahead pattern so it correctly handles closing
parentheses. This allows the project filter (and other filters) to work
properly when nested in parentheses.

- Added tests for project filters in parentheses (both frontend and backend)
- Backend tests confirm the backend already handled this correctly
- Frontend regex pattern now matches the backend behavior

Fixes #1645

pkg/models/task_collection_filter_test.go

@@ -284,4 +284,31 @@ func TestParseFilter(t *testing.T) {
 			assert.Equal(t, 0, date.Year())
 		}
 	})
+	t.Run("project with parentheses", func(t *testing.T) {
+		result, err := getTaskFiltersFromFilterString("( project = 1 )", "UTC")
+
+		require.NoError(t, err)
+		require.Len(t, result, 1)
+		require.Len(t, result[0].value, 1)
+
+		firstSet := result[0].value.([]*taskFilter)
+		assert.Equal(t, "project_id", firstSet[0].field)
+		assert.Equal(t, taskFilterComparatorEquals, firstSet[0].comparator)
+		assert.Equal(t, int64(1), firstSet[0].value)
+	})
+	t.Run("project with OR in parentheses", func(t *testing.T) {
+		result, err := getTaskFiltersFromFilterString("( done = false || project = 1 )", "UTC")
+
+		require.NoError(t, err)
+		require.Len(t, result, 1)
+		require.Len(t, result[0].value, 2)
+
+		firstSet := result[0].value.([]*taskFilter)
+		assert.Equal(t, "done", firstSet[0].field)
+		assert.Equal(t, taskFilterComparatorEquals, firstSet[0].comparator)
+		assert.Equal(t, false, firstSet[0].value)
+		assert.Equal(t, "project_id", firstSet[1].field)
+		assert.Equal(t, taskFilterComparatorEquals, firstSet[1].comparator)
+		assert.Equal(t, int64(1), firstSet[1].value)
+	})
 }