fix: sync pyproject.toml dependencies with requirements.txt and add CodeQL SAST workflow

[namann5]

Summary

pyproject.toml declares runtime dependencies that are inconsistent with �ackend/requirements.txt. Three critical packages — cryptography, httpx, and openai — are present in
equirements.txt but missing from pyproject.toml.

This means any installation via pip install . or future PyPI publication silently omits these packages, causing runtime failures in core features:

Missing Package	Broken Feature	Impact
cryptography>=42.0.0	VaultCrypto AES-256-GCM encryption (�ackend/secuscan/vault.py)	Credential vault raises ImportError; all stored secrets become inaccessible
httpx[cli]>=0.28.1	Webhook notification delivery (�ackend/secuscan/notification_service.py)	All webhook/Slack notifications silently fail
openai>=1.0.0	AI Executive Summary (�ackend/secuscan/ai_summary.py)	AI summary feature raises ImportError at call time

Changes

• pyproject.toml: Add cryptography>=42.0.0, httpx[cli]>=0.28.1, openai>=1.0.0 to match �ackend/requirements.txt and setup.sh

Uses httpx[cli] (not plain httpx) to match the extras already installed by setup.sh.

Verification

• Dependency list matches �ackend/requirements.txt
• No merge conflicts with upstream/main

Closes #1703

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[utksh1]

Thanks for the work here. This PR needs to be reshaped before merge:\n\n1. The dependency-sync part appears stale on current main, and parts of it would actually regress declarations (for example, changing httpx[cli] to plain httpx).\n2. The CodeQL workflow may be valuable, but it should be proposed in a clean, focused PR instead of being bundled with an obsolete dependency-sync change.\n3. Please rebase on current main and resubmit only the still-relevant part of this work.\n\nIf you want to keep the CodeQL addition, open a single-purpose PR for that alone.

[namann5]

Reshaped per feedback — CodeQL and .python-version removed, rebased on current main. Now it's just the pyproject.toml fix adding the three missing runtime deps (cryptography, httpx[cli], openai). Used httpx[cli] to match setup.sh so nothing regresses.

@utksh1