Debug customer issues

[WayneJr]

• Set up the assessment to run against local Postgres in Docker instead of requiring live Supabase credentials.
• Added a backend “Challenge Mode” fallback so the app can start cleanly when Supabase credentials are missing.
• Fixed backend database pool initialization to use DATABASE_URL correctly with async Postgres connections.
• Prevented Supabase connection-pool startup/shutdown failures when the assessment is running in local-only mode.
• Fixed tenant isolation in dashboard revenue caching by including tenant_id in the cache key.
• Fixed cross-tenant revenue leakage on refresh, addressing the privacy issue described in ASSIGNMENT.md.
• Fixed revenue summary filtering to support explicit month and year query parameters.
• Added validation so month and year must be provided together for dashboard revenue queries.
• Fixed monthly revenue calculations to query real reservation data instead of returning placeholder totals.
• Fixed revenue aggregation to scope results by both property_id and tenant_id.
• Fixed date filtering to use each property’s timezone when determining which month a reservation belongs to.
• Fixed revenue totals to preserve decimal precision as strings instead of converting to floating-point numbers too early.
• Fixed frontend revenue formatting to round currency safely and detect sub-cent precision issues.
• Added frontend support for requesting month/year-filtered dashboard summaries.
• Fixed profile endpoint behavior so users without an existing profile/preferences row still receive valid default data.
• Fixed profile updates to create missing user_profiles rows instead of failing when no record exists yet.
• Fixed preferences updates to create missing user_preferences rows instead of returning “not found”.
• Fixed avatar upload to upsert the user profile before saving the new avatar URL.
• Fixed bootstrap fallback parsing so the frontend reads the /api/v1/profile response shape correctly.
• Fixed frontend API base URL resolution for localhost development so profile/bootstrap requests hit the backend correctly.