* fix(supply-chain): use ArcGIS timestamp syntax for PortWatch date filter
The PortWatch seed loop was silently failing on every cycle because
`date >= <epoch_ms>` is not valid ArcGIS Feature Service syntax.
ArcGIS requires `date >= timestamp 'YYYY-MM-DD HH:MM:SS'`.
This caused: no chart history, no transit counts, no WoW% in the
Supply Chain panel chokepoints tab (all added in PRs #1560/#1572/#1577).
Verified: 13/13 chokepoints return 175 days of history with the fix.
Also adds chokepointTransits to health.js STANDALONE_KEYS and SEED_META
so the transit counter seed freshness is monitored.
* fix(supply-chain): preserve full UTC time in PortWatch timestamp filter
pwEpochToTimestamp() was hardcoding 00:00:00, expanding the 180-day
window to the start of that UTC date. Now preserves HH:MM:SS from the
original epoch to match the intended query boundary exactly.
259cbd17d4