Add funding, CI workflow, clean up unused screenshots

.github/FUNDING.yml

@@ -0,0 +1 @@
+ko_fi: gigliof

.github/workflows/ci.yml

@@ -0,0 +1,33 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  frontend:
+    name: Frontend — type-check & test
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: pnpm/action-setup@v4
+        with:
+          version: 9
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 20
+          cache: pnpm
+
+      - name: Install dependencies
+        run: pnpm install --frozen-lockfile
+
+      - name: Type-check
+        run: pnpm --filter frontend exec tsc --noEmit
+
+      - name: Test
+        run: pnpm test --reporter=verbose

README.md

@@ -18,7 +18,7 @@ A browser-based piano practice tool. Drop in a **MIDI file**, a **MusicXML score
 
 | Sheet music | All views | Settings |
 |---|---|---|
-| ![Sheet music](docs/screenshot-sheet.png) | ![All views](docs/screenshot-all.png) | ![Settings](docs/screenshot-settings.png) |
+| [![Sheet music](docs/screenshot-sheet.png)](docs/screenshot-sheet.png) | [![All views](docs/screenshot-all.png)](docs/screenshot-all.png) | [![Settings](docs/screenshot-settings.png)](docs/screenshot-settings.png) |
 
 ## Features