End-to-end integration and smoke test suite

Start by setting up the mock adapter registry — a simple in-memory map from integration type key to a mock handler that returns configurable responses. Use Supabase's local CLI (`supabase start`) to spin up a local Postgres instance for run_log and health_check tables. For Vault mock, create a simple key-value store seeded with test credentials keyed by org_id + integration_type. Structure tests so each suite is independently runnable.

Pay special attention to the status machine in HealthMonitor — tests must cover every valid transition (unknown→healthy, healthy→degraded, degraded→failed) and invalid transitions must be asserted to be no-ops. For timeout simulation, use a configurable delay in the mock adapter and set the Edge Function's timeout threshold to a low value (e.g., 500ms) in the test config. Avoid sharing mutable state between test cases to prevent flakiness.

This task IS the testing task. Write integration tests using Deno's built-in test runner for Edge Functions and flutter_test for any Dart-side invocation layers. Structure tests in three suites: (1) EdgeFunctionSuite — dispatch, credential retrieval, adapter routing, and response shape; (2) SyncSchedulerSuite — cron config read, run_log lifecycle, Edge Function invocation, status update; (3) HealthMonitorSuite — endpoint check, result storage, status transition. Each suite must have at least one happy-path and two negative-path tests.

Use beforeEach/afterEach hooks to reset mock state and database rows. Target 100% coverage of all public Edge Function handler branches. Mock all external HTTP calls using a local mock server (e.g., Deno's built-in fetch mock or a lightweight HTTP mock library).