[client] egl: add cached uniforms and multipass effects

Replace the per-frame uniform list with stable, name-cached handles that
retain their values across shader recompilation. Track dirty uniforms so
only changed values are uploaded, reducing redundant GL calls and buffer
management.

Add a reusable effect-pass pipeline with per-pass shaders, samplers,
formats, resolutions, and intermediate render targets. This makes
external effects easier to integrate and supports arbitrary multipass
chains.

Migrate the desktop, cursor, damage, 24-bit, downscale, CAS, and FSR
rendering paths to the new APIs. Also ensure framebuffer objects are
released correctly.

client/renderers/EGL/CMakeLists.txt

@@ -85,9 +85,9 @@ add_library(renderer_EGL STATIC
   cursor.c
   damage.c
   framebuffer.c
+  effect.c
   postprocess.c
   ffx.c
-  filter.c
   filter_24bit.c
   filter_ffx_cas.c
   filter_ffx_fsr1.c