Make service connection config editable on service page

The service detail page showed non-secret connection config (base_url,
user_id, username, timeout_seconds) as read-only. Render schema-driven
editable inputs (reusing the create-dialog pattern) with a draftConfig
state hydrated from the instance, and unify the save button to persist
both config and secrets. Number fields render as type=number; the base_url
schema description surfaces as helper text.

backend/.pi-map.md

@@ -4,13 +4,13 @@ dir: backend
 index: backend/.pi-map.index.md
 
 ## role
-FastAPI backend service providing JWT-protected REST APIs for Jellyfin media browsing, SSH file inspection, and server monitoring.
+FastAPI backend service providing Jellyfin media browsing, SSH file inspection, server monitoring, and JWT-protected API endpoints.
 ## files
 - Dockerfile | Builds a Docker container for a Python 3.11 backend API service using uvicorn | dep: python:3.11-slim, pip, uvicorn, pyproject.toml-based package
 - README.md | Documentation describing the setup, configuration, Docker deployment, and API endpoints for a FastAPI backend that provides Jellyfin media browsing, SSH file inspection, server monitoring, and JWT-protected access. | dep: FastAPI, uvicorn, pydantic-settings, Docker Compose
 - pyproject.toml | Project configuration file defining dependencies, build system, linting, and testing settings for a FastAPI media library viewer backend. | dep: FastAPI, uvicorn, pydantic-settings, paramiko, requests, python-dotenv, pandas, PyJWT, prometheus-client, python-json-logger, cryptography, hatchling, ruff, pytest, httpx
 ## arch
-Layered Python 3.11 API using FastAPI with uvicorn ASGI server, containerized via Docker for deployment.
+Containerized Python 3.11 REST API using FastAPI/uvicorn with JWT authentication, configured via pyproject.toml with linting and testing support.
 ## tags
 uvicorn, fastapi, python, backend, pyproject, settings, docker, api
 ## symbols