chore: remove the TypeScript code from the repository (#2048)

This deletes the bulk of the `codex-cli` folder and eliminates the logic
that builds the TypeScript code and bundles it into the release.

Since this PR modifies `.github/workflows/rust-release.yml`, to test
changes to the release process, I locally commented out all of the "is
this commit on upstream `main`" checks in
`scripts/create_github_release.sh` and ran:

```
./codex-rs/scripts/create_github_release.sh 0.20.0-alpha.4
```

Which kicked off:

https://github.com/openai/codex/actions/runs/16842085113

And the release artifacts appear legit!

https://github.com/openai/codex/releases/tag/rust-v0.20.0-alpha.4

.github/workflows/codex.yml

@@ -39,37 +39,6 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v4
 
-      # We install the dependencies like we would for an ordinary CI job,
-      # particularly because Codex will not have network access to install
-      # these dependencies.
-      - name: Setup Node.js
-        uses: actions/setup-node@v4
-        with:
-          node-version: 22
-
-      - name: Setup pnpm
-        uses: pnpm/action-setup@v4
-        with:
-          version: 10.8.1
-          run_install: false
-
-      - name: Get pnpm store directory
-        id: pnpm-cache
-        shell: bash
-        run: |
-          echo "store_path=$(pnpm store path --silent)" >> $GITHUB_OUTPUT
-
-      - name: Setup pnpm cache
-        uses: actions/cache@v4
-        with:
-          path: ${{ steps.pnpm-cache.outputs.store_path }}
-          key: ${{ runner.os }}-pnpm-store-${{ hashFiles('**/pnpm-lock.yaml') }}
-          restore-keys: |
-            ${{ runner.os }}-pnpm-store-
-
-      - name: Install dependencies
-        run: pnpm install
-
       - uses: dtolnay/rust-toolchain@1.88
         with:
           targets: x86_64-unknown-linux-gnu