Add native address search with geocoding for location presets, remove itilog.com link

Adds a new AddressSearchScreen: enter an address on a dedicated
keyboard (with a special-character page for common European accented
letters), geocode it via the free OpenStreetMap Nominatim service,
confirm the found place, optionally name it, and save it as a new
location preset - no external website needed anymore.

Reachable both from Location Presets > "+" (choice between "by
address" and manual coordinates) and, for new users, from a one-time
FirstRunLocationScreen shown right after the language picker on first
boot, explaining why an exact address beats automatic IP geolocation
and letting them set it up immediately (skippable).

Removes the itilog.com link/tip added in the previous commit (Location
Presets info screen, all 6 languages, and the README) - superseded by
this native in-app flow.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/i18n_en.h

@@ -205,7 +205,21 @@ static const char* const I18N_EN[] = {
     "Weather",
     "The weather icon shows the current weather for your active location. If a location preset is selected, its weather is shown instead.",
 
-    "Tip: at itilog.com (https://www.itilog.com/) you can enter your address for free and instantly get its exact coordinates. It's worth it - automatic IP-based location can easily be off by 20-30 km, so you might hear a plane overhead while the radar stays empty. With the exact coordinates entered as a preset, the proximity LED really does blink in sync with the aircraft above you.",
+    "Add Location",
+    "Enter coordinates",
+    "Search by address",
+    "Enter your address",
+    "Searching...",
+    "No results found. Try a different spelling.",
+    "Search failed. Check your WiFi connection.",
+    "Is this the right place?",
+    "Use this location",
+    "Try again",
+    "Cancel",
+    "Set Your Exact Location",
+    "Automatic IP-based location can easily be 20-30 km off - you might hear a plane overhead while the radar stays empty. Enter your address now for exact coordinates and a much better experience. The proximity LED will then really blink in sync with the aircraft above you. You can also do this later anytime via Menu > Flight Options > Location Presets.",
+    "Enter Address",
+    "Skip",
 };
 
 static_assert(sizeof(I18N_EN) / sizeof(I18N_EN[0]) == (size_t)StringId::COUNT,