[CanReader]

Uses the engine's new include library and per-frame data (SleakEngine#232).

• Voxel, water, flat and GL lighting shaders include sleak/shadow_light.glsl and sleak/frame.glsl instead of carrying their own copies of the shadow light block.
• Water reads time from uFrame.Time; the water material no longer smuggles the game clock through its tiling.
• The build compiles game Vulkan shaders against both include folders (GameShaders target), so an engine include change rebuilds game SPIR-V too, and stages them over the committed copies. scripts/compile_shaders.sh passes the same include paths. Configuring fails if the game tries to shadow the engine's include/sleak/.
• CI checks committed game SPIR-V against include changes (including Engine pin changes) and validates the GL shaders.

Vulkan captures of the four fixed views are byte-identical. On OpenGL, only water pixels change (lake and hill views), because water now runs on the engine clock instead of the game's summed frame times; with the old clock restored the GL captures match too.

The Engine pin moves to the engine merge commit once SleakEngine#232 lands.