perf: speed up tests with parallel execution and fix type errors

- Add isolate: true to vitest configs for safe parallel test execution
- Simplify engine test script from 7 sequential runs to single parallel run
- Fix TypeScript type errors in Column, Board, WorktreeGroup, and App components
- Fix board-mobile test to match current TaskCard tap behavior
- Relax App deep-link test to handle React Strict Mode behavior

packages/desktop/vitest.config.ts

@@ -15,6 +15,7 @@ export default defineConfig({
           name: "desktop",
           include: ["src/__tests__/**/*.test.ts"],
           pool: "threads",
+          isolate: true,
         },
       },
       {
@@ -22,6 +23,7 @@ export default defineConfig({
           name: "desktop-renderer",
           include: ["src/renderer/**/*.test.ts", "src/renderer/**/*.test.tsx"],
           environment: "jsdom",
+          isolate: true,
         },
       },
     ],