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/tooltip.js

@@ -0,0 +1,91 @@
+// ── Global tooltip system ──
+// Replaces native title="" with styled tooltips. Supports:
+//   data-tip="short text"        — single-line tooltip (replaces title)
+//   data-help="line1\nline2"     — multi-line inline help (shown on hover)
+
+const SHOW_DELAY = 400;
+const HIDE_DELAY = 100;
+const OFFSET = 8;
+
+let tipEl = null;
+let showTimer = null;
+let hideTimer = null;
+let currentTarget = null;
+
+function create() {
+    if (tipEl) return;
+    tipEl = document.createElement('div');
+    tipEl.id = 'tooltip';
+    tipEl.setAttribute('role', 'tooltip');
+    document.body.appendChild(tipEl);
+}
+
+function show(target) {
+    clearTimeout(hideTimer);
+    if (currentTarget === target) return;
+    currentTarget = target;
+    create();
+
+    const tip = target.dataset.tip || '';
+    const help = target.dataset.help || '';
+    if (!tip && !help) { hide(); return; }
+
+    if (help) {
+        tipEl.classList.add('tooltip-help');
+        tipEl.innerHTML = help.replace(/\\n/g, '<br>');
+    } else {
+        tipEl.classList.remove('tooltip-help');
+        tipEl.textContent = tip;
+    }
+
+    tipEl.style.visibility = 'hidden';
+    tipEl.style.display = 'block';
+
+    const rect = target.getBoundingClientRect();
+    const tipRect = tipEl.getBoundingClientRect();
+
+    let top, left;
+    const spaceBelow = window.innerHeight - rect.bottom;
+    const spaceAbove = rect.top;
+
+    if (spaceBelow >= tipRect.height + OFFSET || spaceBelow >= spaceAbove) {
+        top = rect.bottom + OFFSET;
+        tipEl.classList.remove('tooltip-above');
+    } else {
+        top = rect.top - tipRect.height - OFFSET;
+        tipEl.classList.add('tooltip-above');
+    }
+
+    left = rect.left + rect.width / 2 - tipRect.width / 2;
+    left = Math.max(8, Math.min(left, window.innerWidth - tipRect.width - 8));
+    top = Math.max(4, top);
+
+    tipEl.style.top = top + 'px';
+    tipEl.style.left = left + 'px';
+    tipEl.style.visibility = '';
+}
+
+function hide() {
+    currentTarget = null;
+    if (tipEl) tipEl.style.display = 'none';
+}
+
+function onEnter(e) {
+    const target = e.target.closest('[data-tip],[data-help]');
+    if (!target) return;
+    clearTimeout(hideTimer);
+    showTimer = setTimeout(() => show(target), SHOW_DELAY);
+}
+
+function onLeave(e) {
+    const target = e.target.closest('[data-tip],[data-help]');
+    if (!target) return;
+    clearTimeout(showTimer);
+    hideTimer = setTimeout(hide, HIDE_DELAY);
+}
+
+document.addEventListener('pointerenter', onEnter, true);
+document.addEventListener('pointerleave', onLeave, true);
+document.addEventListener('pointerdown', () => { clearTimeout(showTimer); hide(); }, true);
+document.addEventListener('keydown', () => { clearTimeout(showTimer); hide(); }, true);
+document.addEventListener('scroll', () => { clearTimeout(showTimer); hide(); }, true);