Landing atmosphere: galaxy title, shader river, forested banks

[mracette]

What this is

A working prototype that reworks the landing page's flat treeline into a moonlit river receding through forested banks, art-directed against an AI-generated poster. Paused at prototype stage — see the honest assessment below before considering a merge.

Changes

• Galaxy title art: the hero h1 text and stardust spill are replaced by a generated title image (nebula woven through the script lettering) on a black plate, composited with mix-blend-mode: screen so it melts into the night sky. LoadingScreen uses it too.
• LandingPageWater (new): the entire water surface is one quad + fragment shader — winding light lane with wavy dashed reflections, dark bank reflections, waterline sliver, perspective-compressed ripple bands, stardust swirl isolines, twinkling glints. Owns the shared channel geometry (channelAt(t), emitted in both TS and GLSL).
• LandingPageTreeline (reworked): 9 individual tree silhouettes (image gen → potrace SVGs) planted along both shorelines with continuous per-tree depth (size/tint/blur/base all derived per tree — no row seams), exponential size falloff, hillside rise, deterministic hero trees anchoring the frame edges. The old strip survives as the far forest wall.
• LandingPageFog (reworked): re-anchored on the channel horizon; warm ember at the channel mouth behind the far trees, two breathing glow pockets backlighting the banks, channel-confined shore/horizon mist. Front fog removed.
• Sub-LSB dithering in every gradient shader (fixes 8-bit banding over the near-black scene).
• docs/landing-scene-learnings.md: retrospective with the reusable techniques, named visual failure modes, and the performance architecture to use next time.

Known issues (why this is a draft)

• Performance: resize/initial load re-rasterizes two full-viewport canvases (~200 sprite draws, CPU ctx.filter blurs, full texture re-uploads). Visibly stuttery on resize. The learnings doc describes the fix (pre-baked sprite atlas, re-layout instead of re-rasterize).
• Billboard lighting ceiling: light can't fall on flat silhouettes — no rim light or per-tree mist response. The scene reads best as graphic silhouette-and-glow, not simulated 3D.

Verified at desktop and 390px viewports; typecheck and all 106 unit tests pass.

https://claude.ai/code/session_01Caja5tPzzt6wzwu5DYaYnk