Allow selecting problems (#1568)

Fixes #672 


<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Add selectable problem rows with Select all/Clear all and Fix N
selected, and update tests to cover selection behavior.
> 
> - **UI (Problems panel)**:
> - Add checkbox selection for each problem row (`ProblemItem`) with row
click-to-toggle, `data-testid="problem-row"`, and accessibility
attributes.
> - Introduce selection state in `_Problems` with auto-select-all on
report load; provide Select all / Clear all controls.
> - Change Fix button to operate on selected problems only, showing
dynamic label `Fix N problem(s)` and disabled when none selected.
> - Wire `RecheckButton` to clear selection before rechecking; minor
hover style tweaks; add `Checkbox` component.
> - **E2E Tests**:
> - New test: selecting specific problems and fixing only selected; add
snapshots for prompt content.
> - Update manual edit tests (React/Vite, Next.js) to assert Fix button
enabled/disabled and counts; remove old ARIA snapshots.
>   - Minor import addition for `Timeout` and related expectations.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
8324e26f9d2d265e7e0d1f1b7538e2a8db40f674. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

e2e-tests/snapshots/problems.spec.ts_problems---manual-edit-next-js-1.aria.yml

@@ -1,10 +0,0 @@
-- img
-- text: 1 error
-- button "Run checks":
-  - img
-- button "Fix All":
-  - img
-- img
-- img
-- text: src/bad-file.tsx 2:3
-- paragraph: Cannot find name 'nonExistentFunction'.

e2e-tests/snapshots/problems.spec.ts_problems---manual-edit-next-js-2.aria.yml

@@ -1,4 +0,0 @@
-- paragraph: No problems found
-- img
-- button "Run checks":
-  - img

e2e-tests/snapshots/problems.spec.ts_problems---manual-edit-react-vite-1.aria.yml

@@ -1,10 +0,0 @@
-- img
-- text: 1 error
-- button "Run checks":
-  - img
-- button "Fix All":
-  - img
-- img
-- img
-- text: src/bad-file.tsx 2:1
-- paragraph: Cannot find name 'nonExistentFunction'.

e2e-tests/snapshots/problems.spec.ts_problems---manual-edit-react-vite-2.aria.yml

@@ -1,4 +0,0 @@
-- paragraph: No problems found
-- img
-- button "Run checks":
-  - img

e2e-tests/snapshots/problems.spec.ts_problems---select-specific-problems-and-fix-1.aria.yml

@@ -0,0 +1,21 @@
+- paragraph: "Fix these 2 TypeScript compile-time errors:"
+- list:
+  - listitem: src/bad-file.tsx:2:1 - Cannot find name 'nonExistentFunction1'. (TS2304)
+- code: const App = () => <div>Minimal imported app</div>; nonExistentFunction1(); // <-- TypeScript compiler error here nonExistentFunction2();
+- list:
+  - listitem: src/bad-file.tsx:4:1 - Cannot find name 'nonExistentFunction3'. (TS2304)
+- code: nonExistentFunction2(); nonExistentFunction3(); // <-- TypeScript compiler error here
+- paragraph: Please fix all errors in a concise way.
+- img
+- text: bad-file.ts
+- button "Edit":
+  - img
+- img
+- text: "src/bad-file.ts Summary: Fix 2 errors and introduce a new error."
+- paragraph: "[[dyad-dump-path=*]]"
+- button:
+  - img
+- img
+- text: less than a minute ago
+- button "Retry":
+  - img

e2e-tests/snapshots/problems.spec.ts_problems---select-specific-problems-and-fix-1.txt

@@ -0,0 +1,19 @@
+===
+role: user
+message: Fix these 2 TypeScript compile-time errors:
+
+1. src/bad-file.tsx:2:1 - Cannot find name 'nonExistentFunction1'. (TS2304)
+```
+const App = () => <div>Minimal imported app</div>;
+nonExistentFunction1(); // <-- TypeScript compiler error here
+nonExistentFunction2();
+```
+
+2. src/bad-file.tsx:4:1 - Cannot find name 'nonExistentFunction3'. (TS2304)
+```
+nonExistentFunction2();
+nonExistentFunction3(); // <-- TypeScript compiler error here
+```
+
+
+Please fix all errors in a concise way.