Debug view improvements, warp animation

* Add a visible frame one tile beyond the normal screen in debug mode.

* Fix the display of motion paths for mounted traps in debug mode.

* Add an animation for the warp trap.

SPEC.md

@@ -40,8 +40,9 @@ labeled colored rectangle, so the game is fully playable with zero assets.
   cell's pixel rect is `(col*tile, row*tile, tile, tile)`.
 - Y increases downward (screen convention).
 - The window is sized **once** at startup to fit the tallest and widest level
-  (plus a HUD band of 46 px on top; minimum window width 480 px). It is never
-  resized afterward — recreating the display mid-session makes the OS window
+  (plus a HUD band of 46 px on top; minimum window width 480 px; plus the debug
+  overscan margin of §14 for any level shown in debug). It is never resized
+  afterward — recreating the display mid-session makes the OS window
   flicker/close. Each level's play area is a surface of its own pixel size,
   centered within the fixed window below the HUD; smaller levels are
   letterboxed with a dark background.
@@ -388,7 +389,10 @@ blocks: `type: block, invisible: true, count: [w, h]`.)
 ### 13.4 `warp`
 An invisible tile that teleports the player to `to: [col, row]` on contact
 (zeroing velocity). It re-arms only once the player has left the tile, so it
-fires once per entry.
+fires once per entry. On activation a brief **aura** flashes at both the source
+and destination tiles and fades out over ~0.35 s (expanding/thinning rings drawn
+procedurally, no sprite), so the teleport reads on screen even though the tile
+itself is invisible.
 
 ### 13.5 `phase_block`
 Invisible and intangible until its `trigger` fires, then it fades into a solid
@@ -414,7 +418,15 @@ levels) reveals everything normally hidden:
 - fake blocks tinted, invisible walls tinted, warps tinted with a line to their
   destination, dormant phase blocks ghosted, not-yet-sprung spikes marked,
 - crumbled-away blocks shown as ghosts,
-- moving blocks draw their travel path (waypoints + connecting lines).
+- moving blocks draw their travel path (waypoints + connecting lines),
+- an **overscan margin** of `DEBUG_VIEW_MARGIN` tiles (default 1) is revealed on
+  every side, so geometry just off the map — e.g. an invisible catch-wall a step
+  off-screen — is visible instead of clipped. The play surface is enlarged and
+  all drawing is shifted into it (`Level.render_offset`, a draw-only translation;
+  physics stays in true coordinates). The off-map region is shaded, its grid
+  labels run negative / past the map, and the **true runtime viewport is
+  outlined** so it's clear what's actually on screen during play. The window is
+  sized at startup to include this margin for any level shown in debug.
 
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