OMR Projection Now Order-Proof: Map by question_set_id, Not Position (Closes #148)

[Kanika0306]

PR Description

Problem

OMR option projection relied on positional alignment between quiz question sets and aggregated results.
When ordering differed, mapping became incorrect and could produce wrong option placeholders.

What this PR changes

1. Replaced positional/index-based mapping with deterministic mapping by question_set_id.
2. Added strict duplicate-ID protection to prevent silent overwrites.
3. Added safe handling for missing/partial aggregated results to avoid crashes.
4. Preserved existing API shape and behavior while fixing correctness.
5. Added targeted tests for order independence and duplicate-ID detection.

Files Changed

1. quizzes.py
2. test_quizzes.py

Validation

1. Targeted tests pass (test_quizzes).
2. Full suite passes locally: 61 passed.
3. Local endpoints healthy:
   • http://127.0.0.1:8000/health
   • http://127.0.0.1:8000/docs

Issue

Fixes #148.

[Copilot]

Pull request overview

Fixes incorrect OMR option placeholder projection when question_sets order differs from aggregation output by switching from index-based alignment to deterministic mapping via question_set_id (closes #148).

Changes:

• Added project_omr_option_counts() helper to project OMR option placeholders by question_set_id (order-independent).
• Updated the aggregation pipeline output to include question_set_id and wired the helper into GET /quiz/{quiz_id} OMR flow.
• Added tests for order independence and duplicate question_set_id detection.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
app/routers/quizzes.py	Introduces deterministic question_set_id mapping for OMR option projection and updates aggregation projection accordingly.
app/tests/test_quizzes.py	Adds targeted regression tests for reordered aggregation output and duplicate-ID protection.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Kanika0306]

@copilot apply changes based on the comments in this thread