RE: Fix /api/v1 prefix consistency and add a root resource to the REST API

[ArthurLuciani2]

PR Summary

Problem

Two related issues in the PlantDB REST API:

1. Inconsistent /api/v1 prefixing. Endpoint paths and the URLs embedded in server responses were not consistently including the /api/v1 mount prefix, and there was no clean separation between the API version prefix and a deployment (reverse-proxy) path prefix.
2. Missing resource at the server root. A request to the bare root (http://host:port/, or http://host:port/{prefix}/ behind a proxy) returned 404, because all resources are mounted under /api/v1.

Solution

Introduce two distinct prefix concepts and thread them everywhere:

• API_PREFIX = "/api/v1" — always present, shared truth. The app mounts at /api/v1 only.
• Deployment prefix (deploy_prefix, e.g. /plantdb) — a runtime per-server/per-client constant for reverse-proxy deployments, used only to generate external-facing URLs in responses.

Server

• api_endpoints: the @api_prefix decorator now composes <deploy_prefix>/api/v1/<endpoint> (with proper sanitization) and the Home resource builds its endpoint map via these builders.
• fsdb_rest_api / wsgi: mount at /api/v1 always; deploy_prefix replaces the deprecated api_prefix param; the --api-prefix / API_PREFIX value is honored.
• Scan services (get_scan_info / get_scan_data) and _get_colmap_camera_model thread the prefix into every generated URL (archive, thumbnail, filesUri, camera poses). This fixes two bugs where camera-pose URLs and the nested get_scan_info output lost the prefix.
• Root resource: register a 302 redirect at / to the home endpoint, keeping the deployment prefix in the Location header so clients stay under the proxy path.

Client

• PlantDBClient stores self.prefix and threads it into every api_endpoints.* call.
• URL builders (login_url, scan_url, scan_image_url, …) build fully-prefixed URLs; plantdb_url() now returns the server root including the deployment prefix but not /api/v1.

Tests

• test_api_endpoints.py — deployment-prefix composition across all endpoint builders (78 subtests).
• test_scan_services.py — prefix threading through scan info/data services.
• test_rest_api_deploy_prefix.py — server responses embed the deployment prefix (Home map, ScansTable, Scan).
• test_rest_api_server.py — root-redirect tests (no-prefix and /plantdb cases, exact Location, follow-redirect).
• test_rest_api.py — updated client URL assertions for /api/v1 and the root plantdb_url behavior.

Notes

• test_server_availability() now passes via the new root redirect (GET / → 302 → /api/v1/).
• Existing client and server suites pass; the remaining untracked files (knowledge/, test data, caches) are local artifacts not part of this PR.