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]>

CHANGELOG.md

@@ -1,5 +1,13 @@
 # Changelog
 
+- Size the TomTom daily tile budget to the provider's real free allowance.
+  `TOMTOM_DAILY_TILE_BUDGET` defaulted to 40,000/day against an allowance
+  granted monthly (200,000 tile requests/month), exhausting a month in five
+  days and leaving the traffic layer dead for the rest of the period. The
+  default is now 6,000/day (186,000 over a 31-day month). Corrects the stale
+  "~50k/day" free-tier figure in the proxy, `.env.example` and
+  `DATA_SOURCES.md`. Still an application-side ceiling, not a billing cap.
+
 - Distinguish PARTIAL vessel snapshots from STALE data in the layer panel, with
   accepted-record counts and unchanged retention, freshness and outage safeguards.