[Assets] Build a deterministic versioned cooked asset database

[proggeramlug]

Parent: #126

Problem

tools/bloom-cook is currently texture-focused. A high-end renderer needs deterministic offline processing for meshes, meshlets/LODs, textures, materials, animation, environments, and world dependencies. Runtime parsing of source glTF plus uncompressed/general-purpose texture upload cannot support large scenes, virtualized geometry, or predictable platform memory.

Outcome

A versioned, deterministic, content-addressed cooked asset database with platform/quality variants and an incremental CLI.

Build graph

• Inputs are source assets plus importer/cooker version, platform profile, quality profile, and relevant settings.
• Each output has a stable content hash and explicit dependency hashes.
• Rebuild only invalidated nodes; produce identical bytes for identical inputs/settings.
• Store provenance, source license/path, warnings, and diagnostic names.
• Write atomically; interrupted cooks may not leave valid-looking partial artifacts.

Required processors

Textures

• Preserve color-space/normal/data semantics.
• Generate coverage-preserving alpha mips and normal-aware mips.
• Emit platform formats: desktop BC family (including BC7/BC6H as appropriate), mobile ASTC/ETC fallback, and WebGPU-compatible path; use KTX2/Basis where it is the right transport rather than as a blanket answer.
• Record dimensions, mip offsets, format, alpha mode, and streaming page layout.

Meshes

• Validate/normalize coordinate, index, tangent, skin, and morph data.
• Generate conventional LODs and bounds.
• Provide meshlet/cluster hierarchy/page output needed by the virtual-geometry issue.
• Preserve material boundaries and stable submesh/material IDs.

Materials/animations/environments

• Cook the complete supported glTF material extension data.
• Pack animation clips/skeletons with validated joint mappings and compression metadata.
• Prefilter environment lighting and record color/exposure conventions.

Package/index

• Versioned manifest maps logical asset IDs to variant chunks, dependencies, offsets/sizes, and hashes.
• Support loose development output and packed shipping archives without changing logical IDs.
• Runtime rejects incompatible versions with an actionable recook message.

CLI/API

Provide commands equivalent to:

bloom-cook build <manifest> --platform macos --quality high
bloom-cook inspect <artifact-or-package>
bloom-cook verify <package>
bloom-cook clean --unreferenced

Exact syntax may differ, but output must be scriptable and diagnostics identify source asset/material/node.

Acceptance criteria

• Sponza, Bistro, Damaged Helmet, and a skinned model cook without runtime source glTF parsing in shipping mode.
• Two clean cooks with identical inputs/settings produce byte-identical manifests/chunks.
• Editing one source texture rebuilds that texture and dependent package index, not unrelated meshes/animations.
• Runtime loads the correct adapter/platform variant and reports deliberate fallback.
• Cooked texture memory/quality and mesh load time are benchmarked against the current path.
• Corrupt chunk/hash/version cases are tested and fail safely.
• The cooker emits the cluster/LOD metadata contract required by virtual geometry.
• Documentation includes asset manifest examples, cache location, CI use, and migration from direct source loading.

Likely files

• tools/bloom-cook/
• shared asset-format crate/module (do not duplicate struct layout between cooker/runtime)
• native/shared/src/textures.rs, models*.rs, animation/environment loaders
• package scripts and release workflow

Non-goals

• Runtime streaming policy; covered by the async streaming issue.
• An editor asset browser.
• Removing source-asset loading in development mode.

Dependencies

Can start independently. Coordinate formats with #131, #134, and #137 before freezing v1.