Align admin Chabad Blue theme and Immich precision gates.

Port viewer design tokens to admin shell/login with JRCC branding; add max recognition distance, next-best person margin, stricter detection floor, and tighter auto-accept distance.

backend/api/faces.py

@@ -13,6 +13,7 @@ from sqlalchemy import func
 from sqlalchemy.orm import Session
 
 from backend.api.auth import get_current_user_with_id
+from backend.config import AUTO_ACCEPT_MAX_DISTANCE
 from backend.db.models import Face, Person, PersonEncoding, Photo
 from backend.db.session import get_db
 from backend.schemas.faces import (
@@ -652,6 +653,11 @@ def auto_match_faces(
             qualifying_faces = []
             accept_log_items = []
             for face, distance, confidence_pct in similar_faces:
+                # Immich-style: auto-accept only when very close
+                if float(distance) > AUTO_ACCEPT_MAX_DISTANCE:
+                    skipped_matches += 1
+                    continue
+
                 # Check similarity threshold
                 if confidence_pct < request.auto_accept_threshold:
                     skipped_matches += 1