Fix first-run location screen text overlapping buttons, add native address search tip to presets info screen and README

Shortens the first-run location screen's body text in all 6 languages
and makes its buttons follow the text's actual height instead of a
fixed screen position - the longer German translation previously ran
underneath the "Enter Address"/"Skip" buttons, making it unreadable.

Adds a new info paragraph to the Location Presets "?" screen (all 6
languages) pointing to the native "Search by address" option added in
the previous commit, plus the same tip to the README's Getting Started
section.

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

src/i18n.h

@@ -246,6 +246,14 @@ enum class StringId : uint8_t {
     FIRST_RUN_LOCATION_SET_BTN,
     FIRST_RUN_LOCATION_SKIP_BTN,
 
+    // Zusaetzlicher Info-Absatz im Standort-Presets-Screen (Menue >
+    // Flugoptionen > Standort-Presets > "?") - weist auf den "Per Adresse
+    // suchen"-Weg beim "+"-Button hin (deutlich genauer als die
+    // automatische IP-Standortbestimmung). Ergaenzt die knappe Erwaehnung
+    // in LOCATION_INFO_PARA3 um denselben anschaulichen Vergleich wie im
+    // Ersteinrichtungs-Screen (FIRST_RUN_LOCATION_BODY) und im README.
+    LOCATION_INFO_PARA6,
+
     COUNT
 };