chore(places): vendor MapLibre GL JS + pmtiles.js for the photo map

Vendored for the self-hosted Places map (Approach A: client-side PMTiles
decoding, basemap served as a static file via the existing Range-capable
ServeDir):
- maplibre-gl 5.24.0 (BSD-3) + its CSS
- pmtiles 4.4.1

Also adds static/basemaps/ with a .gitignore (*.pmtiles is operator-provided,
never committed) and a README explaining how to drop in a basemap.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JW6ghFMDtnRYuYNzZhb47M

static/basemaps/.gitignore

@@ -0,0 +1,5 @@
+# The vector basemap is large (tens of MB) and operator-provided — never
+# commit it to the repo. Drop a Protomaps `.pmtiles` here as `basemap.pmtiles`
+# and the existing static file server (tower-http ServeDir, Range-capable)
+# will serve it to the Places map. See README.md.
+*.pmtiles