CI Setup (#171)

Setup CI to run typescript check, eslint on changed files, and unit tests
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----

> [!IMPORTANT]
> Sets up CI workflow to run ESLint, TypeScript checks, and unit tests on pull requests using GitHub Actions.
> 
>   - **CI Setup**:
>     - Adds `.github/workflows/ci.yml` to configure CI for pull requests.
>     - Runs on `ubuntu-latest`.
>   - **Linting and Testing**:
>     - Uses `actions/checkout@v4` for code checkout.
>     - Sets up Node.js 20 with `actions/setup-node@v4`.
>     - Caches `node_modules` using `actions/cache@v4`.
>     - Installs dependencies with `npm ci` if cache is not hit.
>     - Collects changed files with `git diff` and filters for `.js`, `.jsx`, `.ts`, `.tsx`.
>     - Runs `eslint` on changed files if any.
>     - Executes TypeScript checks with `npx tsc --emitDeclarationOnly`.
>     - Runs unit tests with `npm run test`.
> 
> <sup>This description was created by </sup>[<img alt="Ellipsis" src="https://img.shields.io/badge/Ellipsis-blue?color=175173">](https://www.ellipsis.dev?ref=nomic-ai%2Fdeepscatter&utm_source=github&utm_medium=referral)<sup> for 970b2ec. It will automatically update as commits are pushed.</sup>

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.github/workflows/ci.yml

@@ -0,0 +1,51 @@
+name: CI Testing
+on: pull_request
+permissions: read-all
+
+jobs:
+  lint-and-test:
+    name: Run ESLint, TypeScript, and Tests
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 20
+          cache: 'npm'
+
+      - name: cache node modules
+        id: cache-dep
+        uses: actions/cache@v4
+        env:
+          cache-name: cache-node-modules
+        with:
+          path: node_modules
+          key: ${{ runner.os }}-lint-${{ env.cache-name }}-${{ hashFiles('**/package-lock.json') }}
+
+      - name: Install dependencies
+        if: steps.cache-dep.outputs.cache-hit != 'true'
+        run: npm ci
+
+      - name: Collect changed files
+        run: |
+          git diff ${{ github.event.pull_request.base.sha }} ${{ github.sha }} --diff-filter=ACM --name-only | grep -E '\.(js|jsx|ts|tsx)$' > ~/lintable_files || true
+          echo "Files to lint:"
+          cat ~/lintable_files
+
+      - name: Lint
+        run: |
+          if [ -s ~/lintable_files ]; then
+            npx eslint $(cat ~/lintable_files)
+          else
+            echo "No files to lint"
+          fi
+
+      - name: TypeScript Checker
+        run: npx tsc --emitDeclarationOnly
+
+      - name: Run Tests
+        run: npm run test