feat(security): add timeout to PDF compilation subprocesses

[anchapin]

🛡️ Sentinel: [MEDIUM] Add timeout to PDF compilation to prevent DoS

Vulnerability:
The pdflatex and pandoc commands were executed using subprocess.Popen().communicate() without a timeout. In certain scenarios (e.g., waiting for user input, infinite loops in TeX), this could cause the process to hang indefinitely, leading to a Denial of Service (DoS) condition.

Fix:

• Added timeout=30 to process.communicate() calls in cli/generators/template.py.
• Added shell=False to subprocess.Popen calls for explicit security.
• Added exception handling for subprocess.TimeoutExpired to kill the process and raise a descriptive RuntimeError.

Verification:

• Added tests/test_template_generator_security.py which mocks subprocess.Popen to simulate a timeout and verifies that the process is killed and the correct exception is raised.
• Verified that existing tests pass.

---

PR created automatically by Jules for task 11471057020964618685 started by @anchapin

[google-labs-jules]

👋 Jules, reporting for duty! I'm here to lend a hand with this pull request.

When you start a review, I'll add a 👀 emoji to each comment to let you know I've read it. I'll focus on feedback directed at me and will do my best to stay out of conversations between you and other bots or reviewers to keep the noise down.

I'll push a commit with your requested changes shortly after. Please note there might be a delay between these steps, but rest assured I'm on the job!

For more direct control, you can switch me to Reactive Mode. When this mode is on, I will only act on comments where you specifically mention me with @jules. You can find this option in the Pull Request section of your global Jules UI settings. You can always switch back!

New to Jules? Learn more at jules.google/docs.

---

For security, I will only act on instructions from the user who triggered this task.

[sourcery-ai]

Sorry @anchapin, you have reached your weekly rate limit of 500000 diff characters.

Please try again later or upgrade to continue using Sourcery