fix(hover-card): use orientation-aware relationship labels; allow spaces in mention

PersonHoverCard was showing the hovered person as their own parent when stored
as the object side of a PARENT_OF row — now uses chipLabel/otherName from
relationshipLabels (same helpers the person detail page uses) to resolve the
correct name and label from the caller's perspective.

PersonMentionEditor: add allowSpaces:true so typing a last name after a space
no longer exits mention mode mid-query.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/lib/components/PersonMentionEditor.svelte

@@ -123,6 +123,7 @@ onMount(() => {
 				},
 				suggestion: {
 					char: '@',
+					allowSpaces: true,
 					// ─────────────────────────────────────────────────────────────
 					// EXCEPTION to frontend/CLAUDE.md "no client-side API fetch":
 					// Tiptap's suggestion plugin lives entirely on the client and