rename render/ files to UpperCamelCase to match client convention

The render/ tree was the only place in the client still using kebab-case
filenames. Brings ~80 files in line with the rest of src/client/
(BuildPreviewController, TransformHandler, etc.). Directories kept as
they were (name-pass/, fx-pass/, passes/, utils/, debug/) since the
codebase already mixes those.

Two collisions surfaced and got resolved: render/types/ is a directory,
not a file, so its imports kept the lowercase form; and the sed pass
incidentally normalized core/pathfinding imports, which had to be
reverted since that file is actually lowercase on disk despite some
imports having referenced it as ./Types under macOS case-insensitive
resolution.

src/client/controllers/HoverHighlightController.ts

@@ -13,7 +13,7 @@ import { GameView } from "../../core/game/GameView";
 import { Controller } from "../Controller";
 import { MouseMoveEvent } from "../InputHandler";
 import { GameView as WebGLGameView } from "../render/gl";
-import { OWNER_MASK } from "../render/gl/utils/tile-codec";
+import { OWNER_MASK } from "../render/gl/utils/TileCodec";
 import { TransformHandler } from "../TransformHandler";
 
 export class HoverHighlightController implements Controller {