Fix: Support multiple character variants in Present Characters panel

Fixed issues when AI generates multiple character variants (e.g.,
storyteller mode with 'Dottore (Prime)', 'Dottore (Beta)', etc.):

1. Escape quotes in character names to prevent HTML attribute breakage
   - Added escapeHtmlAttr() helper function
   - Prevents names like 'Marianna "Mari"' from breaking HTML

2. Restore avatar lookup for character variants
   - namesMatch() now strips parentheses and quotes from both sides
   - Allows 'Dottore (Prime)' to find 'Dottore' character card avatar
   - Each variant still gets its own card with separate attributes

3. Multiple characters now display correctly in panel
   - Each variant creates its own character object
   - Attributes (Details, Relationship, Stats, Thoughts) don't mix
   - All characters appear in the panel, not just the last one

src/systems/generation/promptBuilder.js

@@ -256,7 +256,7 @@ export function generateTrackerInstructions(includeHtmlPrompt = true, includeCon
 
             // Relationship line (only if relationships are enabled)
             if (relationshipPlaceholders) {
-                instructions += `Relationship: [${relationshipPlaceholders}]\n`;
+                instructions += `Relationship: [(choose one: ${relationshipPlaceholders})]\n`;
             }
 
             // Stats line (if enabled)