Add an AWQ grounding embedder recall gate

[maziyarpanahi]

Description

Adds a 4-bit AWQ recipe for grounding embedders with fail-closed retrieval certification. The grounding path now admits an artifact only when its top-k passage overlap stays within the configured recall-delta tolerance relative to the fp16 parent.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Code refactoring
• Performance improvement
• Test addition/improvement

Changes Made

• Added a grounding-specific AWQ export recipe that uses only the shared committed synthetic calibration passages and records their stable digest.
• Added top-k overlap certification, benchmark-format artifact-size and latency evidence, and fail-closed metadata validation.
• Added a certified grounding embedder loader plus runtime documentation and offline unit coverage.

Testing

• I have added tests that prove my feature works
• New and existing unit tests pass locally with my changes
• I have tested this change with different models/inputs

Commands run:

• make format
• make lint
• make format-check
• .venv/bin/pre-commit run --files openmed/torch/awq_grounding.py openmed/torch/__init__.py tests/unit/torch/test_awq_grounding_recall.py docs/runtimes/awq-grounding.md mkdocs.yml
• .venv/bin/python scripts/release/check_repo_policy.py
• .venv/bin/python -m mkdocs build --strict
• .venv/bin/python -m pytest tests/ -q (5,209 passed, 46 skipped)

Documentation

• I have updated the documentation accordingly
• I have added docstrings to new functions/classes
• I have updated the changelog

Code Quality

• I ran make format, make lint, and make format-check
• For Swift/OpenMedKit changes, I ran make format-swift and make lint-swift
• I have performed a self-review of my own code
• I have commented the synthetic fixture boundary
• My changes generate no new warnings

Dependencies

• I have not added any new dependencies
• OR I have added new dependencies and they are justified because: N/A

Checklist

• I have read the contributing guidelines
• My commits have clear, descriptive messages
• I have organized my commit appropriately

Related Issues

Closes #917

Screenshots/Examples

N/A