Delegate spatial mechanics to Viron server

[dmccoystephenson]

Summary

Replace Roam's JSON file-based spatial data management (environments, grids, locations, entities) with a Viron server as the authoritative backend. Changes must be persisted immediately via the Viron REST API rather than buffered and flushed on shutdown.

Background

Roam currently manages room/grid/location/entity relationships in-memory and serializes them to JSON files on shutdown or room transition via RoomJsonReaderWriter (src/world/roomJsonReaderWriter.py) and related classes. Viron is a Spring Boot REST service (Java 21, PostgreSQL) that manages exactly this hierarchy — environments → grids → locations → entities — through a clean REST API. The Python client services (EnvironmentService, GridService, LocationService, EntityService) already exist in the Viron repo under src/main/python/preponderous/viron/services/.

Requirements

Infrastructure

• Add Viron connection config to config.yml (e.g. vironHost, vironPort) and load it in Config (src/config/config.py)
• Register a VironClient wrapper (or reuse the existing Viron Python service classes directly) in the DI container via src/bootstrap.py
• The Viron server must be running before Roam launches; if the connection fails at startup, Roam should log an error via gameLogging (PR Add structured logging with structlog across codebase #344) and fall back gracefully or exit with a clear message

Data Mapping

Map Roam's domain concepts to Viron's:

Roam	Viron
Room	Environment
Room grid	Grid
Location	Location
DrawableEntity / LivingEntity	Entity

Immediate Persistence

• All state-mutating operations (entity placement, movement, removal, room generation) must call the Viron REST API immediately rather than accumulating in-memory state for later file writes
• Remove or bypass the existing JSON file write paths in RoomJsonReaderWriter.saveRoom(), Stats.save(), and TickCounter.save() for data covered by Viron — stats and tick count may continue using JSON files if they have no Viron equivalent
• Background thread save calls in WorldScreen (src/screen/worldScreen.py) that defer room writes should be replaced with synchronous or async Viron API calls using the existing ThreadPoolExecutor pattern

Read Path

• On room load/transition, fetch environment + grid + location + entity data from Viron via the appropriate service (GET /api/v1/environments/{id}, GET /api/v1/locations/environment/{environmentId}, etc.) instead of reading from room JSON files
• Map.getRoom() and RoomPreloader._loadOrGenerate() (src/world/roomPreloader.py) should query Viron first, then fall back to generating a new room if Viron returns 404

Entity Lifecycle

• When WorldScreen places, gathers, or removes an entity, call PUT /api/v1/locations/{locationId}/entity/{entityId} or DELETE /api/v1/locations/entity/{entityId} immediately
• When a living entity moves between locations (in room.py moveLivingEntities()), update its location in Viron atomically: remove from current location then add to new location
• When a living entity dies (checkForLivingEntityDeaths() in worldScreen.py), call DELETE /api/v1/entities/{id} to remove it from Viron

Save Directory Compatibility

• The pathToSaveDirectory config and associated JSON schemas may be retained for stats, tick count, inventory, and player attributes that have no Viron equivalent
• Room JSON files under saves/*/rooms/ should no longer be written or read for data now owned by Viron

Acceptance Criteria

• Roam reads initial room/entity state from a running Viron server on launch
• All entity placement and movement operations are reflected in Viron immediately (no deferred writes)
• Room transitions query Viron for existing room data before generating new rooms
• Removing or killing entities calls the Viron delete endpoint immediately
• Roam logs a clear error via gameLogging and exits gracefully if Viron is unreachable at startup
• Inventory, stats, tick count, and player attributes continue to persist via existing JSON file mechanism
• All existing tests that do not depend on the JSON room persistence path continue to pass
• New tests cover the Viron client integration (mocked HTTP) for room load, entity placement, movement, and deletion