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/css/style.css

@@ -1,4 +1,32 @@
 body { font-family: var(--t-font-content, 'JetBrains Mono', monospace); }
+
+/* Tooltip system */
+#tooltip {
+    display: none;
+    position: fixed;
+    z-index: 9999;
+    max-width: 280px;
+    padding: 4px 8px;
+    font-family: var(--t-font-pixel, 'Silkscreen', cursive);
+    font-size: 9px;
+    line-height: 1.5;
+    color: var(--t-bright);
+    background: var(--t-surface);
+    border: 1px solid var(--t-border);
+    border-radius: 4px;
+    box-shadow: 0 4px 12px rgba(0,0,0,0.4);
+    pointer-events: none;
+    white-space: nowrap;
+}
+#tooltip.tooltip-help {
+    white-space: normal;
+    padding: 8px 12px;
+    font-size: 10px;
+    max-width: 320px;
+    font-family: var(--t-font-content, 'JetBrains Mono', monospace);
+    color: var(--t-muted);
+    border-left: 3px solid var(--t-accent);
+}
 .font-pixel { font-family: var(--t-font-ui, var(--t-font-pixel, 'Silkscreen', cursive)) !important; }
 .brand { font-family: 'Silkscreen', cursive !important; }
 body.no-scanlines::after { display: none !important; }