Document margin behavior and update model comparison script

- Add section explaining how margin works differently in multi-ref vs
  margin-only matching, with examples showing why margin-only fails
  when using multiple references per logo
- Update run_model_comparison.sh to use optimal threshold (0.70) and
  margin (0.05) based on test results
- Add DINOv2 Large model test to comparison script
- Add threshold optimization test analysis to results document

run_model_comparison.sh

@@ -13,8 +13,8 @@ REFS_PER_LOGO=10
 POSITIVE_SAMPLES=20
 NEGATIVE_SAMPLES=100
 MIN_MATCHING_REFS=3
-THRESHOLD=0.80
-MARGIN=0.10
+THRESHOLD=0.70
+MARGIN=0.05
 SEED=42
 
 # Clear output file and write header
@@ -82,11 +82,29 @@ uv run python "$SCRIPT_DIR/test_logo_detection.py" \
     --clear-cache \
     --output-file "$OUTPUT_FILE"
 
+echo ""
+
+# Test 3: DINOv2 Large
+echo "=== Test 3: DINOv2 Large (facebook/dinov2-large) ==="
+uv run python "$SCRIPT_DIR/test_logo_detection.py" \
+    --num-logos $NUM_LOGOS \
+    --refs-per-logo $REFS_PER_LOGO \
+    --positive-samples $POSITIVE_SAMPLES \
+    --negative-samples $NEGATIVE_SAMPLES \
+    --matching-method multi-ref \
+    --min-matching-refs $MIN_MATCHING_REFS \
+    --use-max-similarity \
+    --threshold $THRESHOLD \
+    --margin $MARGIN \
+    --seed $SEED \
+    --embedding-model "facebook/dinov2-large" \
+    --clear-cache \
+    --output-file "$OUTPUT_FILE"
+
 echo ""
 echo "Results saved to: $OUTPUT_FILE"
 echo ""
 echo "Note: You can also try other models:"
 echo "  - facebook/dinov2-base"
-echo "  - facebook/dinov2-large"
 echo "  - openai/clip-vit-base-patch32"
 echo "  - openai/clip-vit-large-patch14-336"