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.

README.md

@@ -243,14 +243,17 @@ wixl 0.106 has no arm64 support, so Windows/ARM64 ships the portable `.zip`
 
 ## Logging
 
-Every run writes `openra3.log` next to the executable through the vendored
+Every run writes `openra3.log` in a per-user `logs/` folder — on Windows
+`%LOCALAPPDATA%\OpenRA3\logs`, elsewhere `$XDG_STATE_HOME/openra3/logs`
+(falling back to `~/.local/state/openra3/logs`) — created on first use and kept
+out of the binary's own directory, through the vendored
 [`libenderlog`](third_party/libenderlog) module (`import ender.log;`). A file
-sink archives the previous log to `openra3.log.<YYYYmmdd-HHMMSS>` on open, so
+sink archives the previous log to `openra3.<YYYYmmdd-HHMMSS>.log` on open, so
 each run gets its own file; the active file rotates at 4 MiB and the last 10
 archives are kept. Records at **`warn` and above** carry a call stack (Windows
 `CaptureStackBackTrace` / POSIX `execinfo`, because libc++ has no
-`<stacktrace>`). A hard crash also writes `openra3_crash.log` with the faulting
-module and a raw backtrace.
+`<stacktrace>`). A hard crash also writes `openra3_crash.log` alongside it with
+the faulting module and a raw backtrace.
 
 ## Running a skirmish