fix(hover-card): maiden name false positive, placeholder on non-empty editor, card persistence

- PersonHoverCard: alias is compared against both `lastName` and `displayName`
  before showing as maiden name — prevents false positive when alias is stored
  as the full current name (e.g. "Maria Schmidt" ≠ "Schmidt" but name unchanged)
- PersonMentionEditor: data-placeholder was set statically so the CSS ::before
  rule showed the placeholder on any blur even with content; now a $effect
  toggles the attribute based on editor.isEmpty
- TranscriptionReadView: hovering onto the card itself cancels the 150ms close
  timer so the card stays open while reading it; leaving the card closes it
  immediately — onmouseenter/onmouseleave wired through PersonHoverCard props
- hoverCardPosition: removed scrollX/scrollY offset since the card is now
  position:fixed (scroll is already baked into getBoundingClientRect coords)
- MentionDropdown: raised z-index from z-20 to z-50 to render above the hover card
- vite.config.ts: pre-bundle Tiptap packages to avoid HMR waterfall on first load

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

frontend/src/lib/utils/hoverCardPosition.ts

@@ -32,8 +32,6 @@ export const RIGHT_FLIP_THRESHOLD_PX = 300;
 export type Viewport = {
 	viewportWidth: number;
 	viewportHeight: number;
-	scrollX: number;
-	scrollY: number;
 };
 
 export type CardPosition = { top: number; left: number };
@@ -63,7 +61,7 @@ export function computeHoverCardPosition(rect: DOMRect, vp: Viewport): CardPosit
 	left = Math.min(left, vp.viewportWidth - CARD_WIDTH_PX - CARD_GAP_PX);
 
 	return {
-		top: Math.max(0, top + vp.scrollY),
-		left: Math.max(0, left + vp.scrollX)
+		top: Math.max(0, top),
+		left: Math.max(0, left)
 	};
 }