fix(web): stop presenting an unscored case as a failed analysis, and four smaller things

From clicking through the redesigned UI:

- scoring a case without a model registry painted a red failure across a case that had in
  fact analysed fine. It is now a quiet note saying the model term contributes 0, because
  scoring is an optional fourth of the rank, not the analysis.
- the MLflow default moves to port 5001. On macOS, AirPlay Receiver owns 5000, which is why
  the registry answered "403" rather than refusing the connection; docker-compose publishes
  5001 to match.
- a funnel step that kept nothing drew a visible bar. Zero now draws zero.
- "1 candidates".
- the funnel's fixed grid columns forced a horizontal scrollbar on the report.

The report also lists the top undecided candidates now: the first thing anyone opens has no
decisions in it, and "Shortlisted (0)" alone said nothing about what the tool found.

Tests: api 77, web 32; ruff, mypy, svelte-check clean.

api/app/config.py

@@ -10,7 +10,8 @@ class Settings(BaseSettings):
     model_config = SettingsConfigDict(env_file=".env", extra="ignore")
 
     database_url: str = "postgresql+asyncpg://rarelens:rarelens@localhost:5432/rarelens"
-    mlflow_tracking_uri: str = "http://localhost:5000"
+    # docker-compose publishes MLflow on 5001; macOS AirPlay Receiver owns 5000.
+    mlflow_tracking_uri: str = "http://localhost:5001"
     model_name: str = "rarelens-pathogenicity"
     # Registry alias set by `rarelens_ml.train --register` (stages are deprecated in MLflow 3).
     model_alias: str = "production"