fix(tomtom): size the daily tile budget to the real free allowance

TOMTOM_DAILY_TILE_BUDGET defaulted to 40,000 per day against a free
tier that is granted per MONTH, not per day. TomTom currently allows
200,000 Traffic Flow & Incidents tile requests per month
(https://docs.tomtom.com/pricing/), so the default exhausted a user's
entire monthly allowance in five days and left the traffic layer dead
for the rest of the billing period.

The docs contradicted themselves on this. traffic.js described the
free tier as "~50k/day", while .env.example cited the correct 200K
per month two lines below quoting the same 40,000 default. 50k/day
would be 1.5M/month, 7.5x the actual allowance.

Sets the default to 6,000/day. A 31-day month lands at 186,000,
inside the allowance with headroom. Corrects the stale figures in
traffic.js, .env.example and DATA_SOURCES.md.

This remains an application-side safety ceiling, not a billing cap,
and the surrounding text still says so. TomTom's free tier requires
no card, so overrunning it cuts the layer off rather than generating
a charge — but a layer that dies three weeks into every month is
still worth avoiding by default.

Co-Authored-By: Claude Opus 5 <[email protected]>

docs/CURRENT-STATE.md

@@ -3800,7 +3800,8 @@ easier to meet (detection is now on more often), but does not create it.
 - Traffic runs in `sim` mode (white dots, hardcoded speeds) unless `TOMTOM_API_KEY`
   is configured (env or Keychain `tomtom-api`/`api-key`), which enables `live` mode:
   TomTom flow vector tiles via the budget-governed `/api/tomtom` proxy
-  (`.gev-cache/tomtom/`, 120 s TTL, `TOMTOM_DAILY_TILE_BUDGET` default 40k/day),
+  (`.gev-cache/tomtom/`, 120 s TTL, `TOMTOM_DAILY_TILE_BUDGET` default 6k/day,
+  sized so a 31-day month stays inside TomTom's 200K/month free allowance),
   decoded client-side (`flowTiles.js`), matched onto Overpass roads
   (`flowMatch.js`), and rendered as green/amber/red dot color + speed/density
   scaling (`trafficFlowStyle.js`); closures spawn no dots; unmatched roads stay