feat(render): SAGE water/ocean shaders, per-user logs, camera & culling

Terrain pass now ports the SAGE water model (Ocean.fx / OpenSAGE Water.frag): a de-gridded procedural wave normal combined with the retail ra3_deepocean flow and ra3_deepocean_nrm bump maps (appended as the last two terrain-atlas layers, no new backend binding), Schlick fresnel, sky reflection + depth-graded refraction, SAGE diffuse/specular lighting, depth-based transparency, and an underwater tint (UnderwaterDeferred.fx). Mirrored across terrain.frag / dx_terrain.hlsl / webgl_terrain_frag.glsl / webgpu_terrain.wgsl.

Also: logs move to the per-user state dir (%LOCALAPPDATA%\\OpenRA3\\logs, else XDG) and archive as openra3.<stamp>.log; the FPS label shows the active backend; middle-drag camera reset; objects and roads below the water plane are culled.

third_party/libenderlog/README.md

@@ -131,13 +131,13 @@ and `log::set_sinks({...})` replaces them.
 ```cpp
 namespace log = ender::log;
 
-// Archive any existing enderlog.log to enderlog.log.<timestamp>, then start a
+// Archive any existing enderlog.log to enderlog.<timestamp>.log, then start a
 // fresh file for this run. Rotate at 64 KiB and keep the last 5 archives.
 auto sink = log::add_file_sink("enderlog.log", {.max_file_size = 64 * 1024, .max_archives = 5});
 ```
 
 - **No appending onto a previous run.** On open, an existing non-empty
-  `enderlog.log` is renamed to `enderlog.log.<YYYYmmdd-HHMMSS>` before the new
+  `enderlog.log` is renamed to `enderlog.<YYYYmmdd-HHMMSS>.log` before the new
   file is created, so every run gets its own file and the previous run's log is
   preserved. A leftover empty file is simply replaced.
 - `file_options::max_file_size` (0 disables) rotates the active file mid-run the