fix: fix timezone handling across backend and frontend (v0.3.1)

- Add tz.py with local_strftime/to_local helpers that read system.timezone
  from DB and convert UTC datetimes to venue local time before formatting
- Fix all strftime() calls in orders.py, reports.py, printer_service.py
  that were formatting UTC datetimes without timezone conversion
- Fix get_order endpoint returning raw dicts without Z suffix on datetimes,
  causing JS new Date() to treat timestamps as local instead of UTC
- Fix fmtDate() in tokens.js that stripped the T separator before parsing,
  breaking UTC-to-local conversion for all report date displays
- Make open/partially_paid table chips more visually distinct on dashboard

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

local_backend/config.py

@@ -19,7 +19,7 @@ class Settings(BaseSettings):
     CLOUD_URL: str = ""
     SECRET_KEY: str = "change-me-generate-a-long-random-string"
     DATABASE_URL: str = f"sqlite:///{_DB_DEFAULT.as_posix()}"
-    VERSION: str = "0.0.0"
+    VERSION: str = "0.3.1"
     CONNECT_SYNC_INTERVAL_SECONDS: int = 30  # how often to poll for pending online orders
 
     model_config = {"env_file": str(_HERE / ".env"), "env_file_encoding": "utf-8"}