feat(search): case-appropriate disambiguation picker copy (#763)

A 1-item picker now reads "Meintest du …?" (a single direct match auto-selects
and never reaches the picker), while ≥2 keeps the "Person auswählen" framing.
The prompt lives in a visible, non-truncated panel heading (the trigger span
clips at 320px), and the "(auswählen…)" cue is dropped for the 1-item case.
DisambiguationPicker takes heading + showCue props; the page derives both from
ambiguousPersons.length. New search_disambiguation_did_you_mean key in de/en/es.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/messages/en.json

@@ -47,6 +47,7 @@
 	"search_disambiguation_trigger_label": "Several people found — click to choose",
 	"search_disambiguation_cue": "(choose…)",
 	"search_disambiguation_heading": "Choose a person",
+	"search_disambiguation_did_you_mean": "Did you mean {name}?",
 	"search_disambiguation_select_label": "Select {name}",
 	"error_validation_error": "The input is invalid.",
 	"error_internal_error": "An unexpected error occurred.",