feat(core,fuse,gui): Proton theme, photos on the map and an opt-in street map

- The Proton accent preference becomes a whole Proton theme that also
  holds against a GTK theme imported from gtk.css; folders get Proton's
  purple folder icon while it is on.
- Places map markers show one of each town's photos with a count, and
  zoomed in on a town every photo sits where it was taken
  (Request::PlaceLocations). Photos taken on one spot are listed in a
  popover. "Show on map" in the photo viewer goes to the Places map.
- The built-in map draws country borders, sea and land in their own
  colours.
- An opt-in street map from OpenFreeMap (vector tiles drawn with cairo,
  cached on disk up to 256 MB), with the OpenStreetMap credit on the map
  and in About.
- Translations for all catalogs; changelog folded into 2.3.0.

Cargo.lock

@@ -3389,6 +3389,31 @@ dependencies = [
  "system-deps 9.0.0",
 ]
 
+[[package]]
+name = "pangocairo"
+version = "0.22.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bd199a0fef965b3ebda91a929a1ab5e7729538882c68e8de38e1904d2e094757"
+dependencies = [
+ "cairo-rs",
+ "glib",
+ "pango",
+ "pangocairo-sys",
+]
+
+[[package]]
+name = "pangocairo-sys"
+version = "0.22.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a649a616d67ae68539bc85f00fb45d36fba742ed20fc20e6712a15d8ee52bd3f"
+dependencies = [
+ "cairo-sys-rs",
+ "glib-sys",
+ "libc",
+ "pango-sys",
+ "system-deps 9.0.0",
+]
+
 [[package]]
 name = "parking"
 version = "2.2.1"
@@ -3517,7 +3542,9 @@ dependencies = [
  "kamadak-exif",
  "ksni",
  "libadwaita",
+ "pangocairo",
  "pdfs-core",
+ "reqwest",
  "serde",
  "serde_json",
  "tokio",