0.5.0: RUWIO rebrand, vertex bezier, animation paths, welcome focus

- Rename the app to RUWIO: title, APP_NAME, topbar logo (40px PNG),
  welcome dialog header and about dialog switch from the PhSparkle
  glyph to the real logo. Redundant name text next to the logo is
  removed across the board.
- About dialog: logo spans the full dialog width, the bottom Close
  button is gone (close via header X stays).
- Vertex bezier for polygons: each vertex can be Corner / Curve / Split
  curve via right-click. Curve mirrors tangent handles symmetrically,
  split curve keeps them independent. Tangents are fully animatable
  per keyframe — lerp mirrored across all four render pipelines.
- Stage path overlay: selecting a keyframe draws the tween arc between
  the previous and selected keyframe with draggable per-frame dots that
  curve the path via quadratic bezier control points. Other segments
  on the same track render as dashed ghost lines so the full curve is
  visible. Path dots grow + show grab cursor on hover.
- Vertex box-select: click-drag on empty stage while a polygon is
  selected boxes vertices. Shift-click toggles individual vertices
  into/out of the selection. Multi-vertex drag moves all selected at
  once; right-click on a selected vertex applies Corner/Curve/Split
  to all. Tangent handles only render when exactly one vertex is
  selected.
- Welcome dialog focus: opens with the most recent project focused.
  Enter opens it; Tab cycles only through the dialog's real buttons
  (delete icons pulled out of tab order, scrollable body removed from
  tab order). Export-current removed from welcome (not useful on
  startup).
- Modal focus trap: all modals now keep Tab inside the dialog.
- Fill / stroke transparency toggle restores the last real color when
  flipped back on, with a layer-base / asset fallback chain so there's
  always a visible color to restore to. A watcher keeps the restore
  cache in sync with the sampled value.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

index.html

@@ -3,7 +3,7 @@
   <head>
     <meta charset="UTF-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
-    <title>Animatr</title>
+    <title>RUWIO</title>
   </head>
   <body>
     <div id="app"></div>