feat(security): Add authorization checks for share deletion

[Bhagyashri77777]

Description

This PR resolves Issue #585 by securing the share deletion flow to ensure only authorized actors can delete shared analysis results.

Since the current database schema does not explicitly link a user_id to SharedSnippet records, the authorization check ensures that only authenticated users (current_user) can access the deletion endpoint.

Key Changes:

• Backend: Added the delete_share endpoint in backend/app/routers/share.py, enforcing a get_current_user dependency.
• Testing: Added test_delete_share_unauthorized and test_delete_share_authorized in backend/tests/test_share.py to verify that unauthorized requests are rejected (401/403) and valid requests succeed (204).

Fixes #585

Checklist

• I have read the contributing guidelines.
• I have added tests that prove my fix is effective.
• New and existing unit tests pass locally with my changes.

[Bhagyashri77777]

Hi @imDarshanGK!

Just a quick update: I have resolved all the formatting and import sorting issues that the CI pipeline caught (black & isort). All checks are now fully green and passing!

The PR is ready for your review whenever you have the time. Thank you!

[imDarshanGK]

@Bhagyashri77777 Thanks for the contribution.

This PR does not fully resolve Issue #585.

Required changes:

• Add authorization checks so that only the share owner or an admin can delete a shared result.
• Add audit logging for share deletions.
• Add tests covering owner, admin, and unauthorized (403) deletion scenarios.
• Remove unrelated changes from this PR, as it currently includes modifications outside the scope of this issue.
• add video demo

Please update the PR accordingly and request another review.

[github-actions]

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[Bhagyashri77777]

Hi @imDarshanGK,

I have updated the PR to fully resolve Issue #585. Here is what has been addressed:

Removed all unrelated file formatting changes to keep the PR clean.

Added authorization checks to ensure only owners and admins can delete shares.

Added an AuditLog entry upon successful deletion.

Added comprehensive unit tests covering owner, admin, and unauthorized (403) scenarios (passing successfully!).

Attached a video demo of the tests passing below.

The PR is ready for your review. Thank you!

Screen.Recording.2026-07-07.191557.mp4