Fixes CMD parser in Python from_dockerfile method (#1040)

What was happening is that the following snippet:

```dockerfile
CMD ["sleep", "20"]
```

Was incorrectly converted to:

```
sleep, 20
```

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Fixes parsing of Dockerfile CMD/ENTRYPOINT array syntax to a proper
start command and updates tests accordingly.
> 
> - **Python SDK**:
> - `e2b/template/dockerfile_parser.py`: Parse CMD/ENTRYPOINT JSON array
(e.g., `["sleep", "20"]`) into a space-joined command (`sleep 20`) and
set as `start_cmd`.
> - **Tests**:
> - JS SDK and Python (sync/async): Add ENTRYPOINT case and assert
`startCmd`/`_start_cmd` equals `sleep 20`.
> - **Release**:
>   - Changeset: patch bump for `@e2b/python-sdk`.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
ed257ab. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: mishushakov

.changeset/fluffy-shrimps-play.md

@@ -0,0 +1,5 @@
+---
+'@e2b/python-sdk': patch
+---
+
+fixed cmd parser in from_dockerfile

packages/js-sdk/tests/template/methods/fromDockerfile.test.ts

@@ -7,7 +7,8 @@ buildTemplateTest('fromDockerfile', async () => {
   const dockerfile = `FROM node:24
 WORKDIR /app
 COPY package.json .
-RUN npm install`
+RUN npm install
+ENTRYPOINT ["sleep", "20"]`
 
   const template = Template().fromDockerfile(dockerfile)
 
@@ -71,6 +72,11 @@ RUN npm install`
     template.instructions[5].args[0],
     'user'
   )
+  assert.equal(
+    // @ts-expect-error - startCmd is not a property of TemplateBuilder
+    template.startCmd,
+    'sleep 20'
+  )
 })
 
 buildTemplateTest('fromDockerfile with default user and workdir', () => {

packages/python-sdk/e2b/template/dockerfile_parser.py

@@ -1,3 +1,4 @@
+import json
 import os
 import re
 import tempfile
@@ -257,6 +258,14 @@ def _handle_cmd_entrypoint_instruction(
         return
     command = value.strip()
 
+    # Try to parse as JSON (for array format like CMD ["sleep", "infinity"])
+    try:
+        parsed_command = json.loads(command)
+        if isinstance(parsed_command, list):
+            command = " ".join(str(item) for item in parsed_command)
+    except Exception:
+        pass
+
     # Import wait_for_timeout locally to avoid circular dependency
     def wait_for_timeout(timeout: int) -> str:
         # convert to seconds, but ensure minimum of 1 second

packages/python-sdk/tests/async/template_async/methods/test_from_dockerfile.py

@@ -9,7 +9,8 @@ async def test_from_dockerfile():
     dockerfile = """FROM node:24
 WORKDIR /app
 COPY package.json .
-RUN npm install"""
+RUN npm install
+ENTRYPOINT ["sleep", "20"]"""
 
     template = AsyncTemplate().from_dockerfile(dockerfile)
 
@@ -37,6 +38,9 @@ async def test_from_dockerfile():
     assert instructions[5]["type"] == InstructionType.USER
     assert instructions[5]["args"][0] == "user"
 
+    # Start command
+    assert template._template._start_cmd == "sleep 20"
+
 
 @pytest.mark.skip_debug()
 async def test_from_dockerfile_with_default_user_and_workdir():

packages/python-sdk/tests/sync/template_sync/methods/test_from_dockerfile.py

@@ -9,7 +9,8 @@ def test_from_dockerfile():
     dockerfile = """FROM node:24
 WORKDIR /app
 COPY package.json .
-RUN npm install"""
+RUN npm install
+ENTRYPOINT ["sleep", "20"]"""
 
     template = Template().from_dockerfile(dockerfile)
 
@@ -37,6 +38,9 @@ def test_from_dockerfile():
     assert instructions[5]["type"] == InstructionType.USER
     assert instructions[5]["args"][0] == "user"
 
+    # Start command
+    assert template._template._start_cmd == "sleep 20"
+
 
 @pytest.mark.skip_debug()
 def test_from_dockerfile_with_default_user_and_workdir():