Implement the baseline pixel-art ordered-scene renderer

[zoeyrose]

Outcome

Render bounded canonical scenes with exact stable ordering and pixel-art behavior for all consumers.

Scope and invariants

• Consume ordered logical scene records with stable identity, named role, physical level/surface placement, transforms, opacity/blend/cutout, resource reference, semantic tags, and revisions.
• Implement fixed isometric projection, unified painter/depth ordering across neighboring tiles/levels, tall/multipart placement, clipping/culling, target/selection overlays, and pixel-art sampling.
• Produce optional exact semantic identity, depth, coverage, visibility, and painter-key outputs alongside color.
• Reject or diagnose scenes exceeding record/byte/depth/coordinate/resource bounds before partial frame state.
• Keep gameplay visibility/authorization out of renderer; it draws only supplied authorized records.

Acceptance criteria

• M1 corpus covers adversarial overlap/order, transparent/cutout sprites, negative coordinates, multipart/tall objects, surfaces/free-air, missing assets, and bounds.
• Same scene renders identically through client, editor, and offscreen paths within documented color tolerance and exact semantic masks.
• Sorting/culling is deterministic and has measured dense-scene budgets.
• Fuzzed scene bundles cannot panic, allocate unbounded memory, access invalid GPU state, or retain partial revisions.
• No 49-slot or classic packet/cache representation exists.

Dependencies and parallelization

Depends on #5/#6 and the transferred ordered-scene issue. Protocol/server/editor adapters proceed against golden logical scene bundles.

Licensing

Rendering code, shaders, tests, and newly authored fixtures are MIT. Reuse from atrinik/classic sources is allowed only through the audited approved-grantor grant; all other behavior is independently implemented. Bundled assets require exact compatible licenses and notices.