Backend compiler and Frontend Setup (keep-starknet-strange#177)

<!-- enter the gh issue after hash -->

- [ ] issue #
- [ ] follows contribution
[guide](https://github.com/keep-starknet-strange/shinigami/blob/main/CONTRIBUTING.md)
- [ ] code change includes tests

<!-- PR description below -->

Created a simple nodejs script with Express.js to collect two arguments
via post requests

Also I setup the frontend to use ```swr``` to fetch mock data and
simulate how clicking run script will work

Made Pub key to be the default editor when editor is not split and sig
key to be the top editor when split

---------

Co-authored-by: Brandon Roberts <[email protected]>

backend/Dockerfile

@@ -0,0 +1,22 @@
+FROM node:20.5.0
+
+SHELL ["bash", "-c"]
+RUN curl https://get.starkli.sh | sh && \
+    source $HOME/.starkli/env && \
+    starkliup && \
+    git clone https://github.com/asdf-vm/asdf.git ~/.asdf --branch v0.14.1 && \
+    . "$HOME/.asdf/asdf.sh" && \
+    . "$HOME/.asdf/completions/asdf.bash" && \
+    asdf plugin add scarb && \
+    asdf install scarb latest && \
+    asdf global scarb latest
+
+WORKDIR /backend
+
+COPY ./index.js ./package.json ./
+
+RUN npm i
+
+EXPOSE 3000
+
+CMD ["node", "index.js"]

backend/compose.yaml

@@ -0,0 +1,10 @@
+services:
+  web:
+    build: .
+    ports:
+      - "8000:3000"
+    develop:
+      watch:
+        - action: sync
+          path: .
+          target: /backend

backend/index.js

@@ -0,0 +1,64 @@
+const express = require('express');
+const { exec } = require('child_process');
+const app = express();
+const cors = require('cors')
+
+const MAX_SIZE = 350000; // Max script size is 10000 bytes, longest named opcode is ~25 chars, so 25 * 10000 = 250000 + extra allowance
+
+function runShellCommand(command, callback) {
+    exec(command, (error, stdout, stderr) => {
+        if (error) {
+            callback(`Error: ${error.message}`);
+            return;
+        }
+        if (stderr) {
+            callback(stderr);
+            return;
+        }
+        callback(stdout);
+    });
+}
+
+function extractStack(output) {
+    const match = output.match(/\[.*\]/);
+    return match ? match[0] : 'No message found';
+}
+
+app.use(cors());
+app.use(express.json()); 
+
+app.post('/run-script', (req, res) => {
+    const { pub_key, sig } = req.body;
+    if (!pub_key) {
+        return res.status(400).send('Missing public key parameter');
+    }
+    if (pub_key.length > MAX_SIZE || sig.length > MAX_SIZE) {
+        //for a more detailed error message
+        if (pub_key.length > MAX_SIZE) {
+            return res.status(400).send('Script Public Key exceeds maximum allowed size');
+        }
+        if (sig.length > MAX_SIZE) {
+            return res.status(400).send('Script Signature exceeds maximum allowed size');
+        }
+    }
+    const scriptPath = '../tests/text_to_byte_array.sh';
+    const sigCommand = `bash ${scriptPath} "${sig}"`;
+    const pubCommand = `bash ${scriptPath} "${pub_key}"`;
+    runShellCommand(sigCommand, (sigOutput) => {
+        runShellCommand(pubCommand, (pubOutput) => {
+            const modifiedSigOutput = sigOutput.trim().slice(1, -1);
+            const modifiedPubOutput = pubOutput.trim().slice(1, -1);
+            const combinedOutput = `[${modifiedSigOutput},${modifiedPubOutput}]`;
+            const cairoCommand = `scarb cairo-run ${combinedOutput} --no-build`;
+            runShellCommand(cairoCommand, (finalOutput) => {
+                const message = extractStack(finalOutput);
+                res.json({ message });
+            });
+        });
+    });
+});
+
+const PORT = process.env.PORT || 3000;
+app.listen(PORT, () => {
+    console.log(`Server is running on port ${PORT}`);
+});

backend/package.json

@@ -0,0 +1,19 @@
+{
+  "name": "backend",
+  "version": "1.0.0",
+  "main": "index.js",
+  "scripts": {
+    "start": "node index.js"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "description": "",
+  "devDependencies": {
+    "@types/node": "^22.5.0"
+  },
+  "dependencies": {
+    "cors": "^2.8.5",
+    "express": "^4.19.2"
+  }
+}