global tooltip system, migrate all title attrs to data-tip/data-help

New tooltip.js module with styled tooltips (data-tip) and multi-line
inline help (data-help). Migrates all ~70 native title attributes
across index.php, JS modules, and all plugins. Adds inline help on
9 strategic UI elements (split, superview, zen, extract, assets, etc).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

public/js/modules/markdown.js

@@ -146,7 +146,7 @@ export function renderMd(src) {
     const linked = processed.replace(/\[\[([^\]]+)\]\]/g, (_, title) => {
         const card = state.cards.find(c => c.title.toLowerCase() === title.toLowerCase());
         if (card) return `<span class="card-link" data-card-id="${card.id}">${esc(title)}</span>`;
-        return `<span class="card-link broken" title="card not found">${esc(title)}</span>`;
+        return `<span class="card-link broken" data-tip="card not found">${esc(title)}</span>`;
     });
 
     let html = marked.parse(linked);