Build the LTN app for web in GH actions

.github/workflows/book.yml

@@ -1,8 +1,8 @@
-name: Rust docs
+name: Rust docs and WASM app
 on:
   push:
     branches:
-      - master
+      - main
 jobs:
   book:
     name: Build and Deploy
@@ -14,11 +14,20 @@ jobs:
       - name: Install Rust
         uses: hecrj/setup-rust-action@v1
 
+      - name: Install wasm-pack
+        uses: jetli/[email protected]
+
       - name: Update apt
         run: sudo apt-get update
       - name: Install dependencies
         run: sudo apt-get install libasound2-dev libxcb-shape0-dev libxcb-xfixes0-dev libpango1.0-dev libgtk-3-dev
 
+      - name: Cache build
+        uses: actions/cache@v3
+        with:
+          path: target
+          key: doesnt-matter-share-everything
+
       - name: Generate rustdoc
         run: |
             cargo doc --no-deps --workspace --exclude widgetry --document-private-items
@@ -28,6 +37,16 @@ jobs:
             mkdir -p book/book
             mv target/doc book/book/rustdoc
 
+      - name: Built LTN app for web
+        run: |
+            cd web
+            sed -i 's/^APPS=.*/APPS=ltn/' Makefile
+            sed -i 's/new LTN("app");/new LTN("app");\n  app.setAssetsBaseURL("https:\/\/play.abstreet.org\/dev\/data");/' src/web_root/ltn.html
+            npm i
+            make release
+            cp -Rv build/dist ../book/book/web/
+            rm -fv ../book/book/web/ltn/wasm_pkg/.gitignore
+
       - name: Publish HTML
         uses: peaceiris/actions-gh-pages@v3
         with: