Add focused tests across many modules to push overall coverage from
75.45% to ~77%.
New test files:
- test/towerops/snmp/topology_test.exs
- test/towerops/vault_test.exs
- test/towerops/workers/check_worker_test.exs
- test/towerops_web/graphql/resolvers/happy_path_test.exs
- test/towerops_web/graphql/schema_test.exs
- test/towerops_web/live/reports_live_test.exs
Expanded existing tests for: Airos vendor, ProfileWatcher, StormDetector,
LLDP, GpsSync, MikrotikBackupWorker, AdminController, MibController,
MobileController, GeoipController, OnboardingLive, UserResetPasswordLive,
SessionManager, Telemetry, CoverageLive.Show.
Also fix a pre-existing dead test in ApplicationSettingTest where the
schema default for value_type made the 'invalid without value_type' test
unreachable.
wire time_format into scope, add settings UI selector, change defaults
to 24h, and replace all user-facing Calendar.strftime calls with
centralized TimeHelpers using the user's timezone and time format.
