M0: RetroAsset native asset foundation

[pgousdal]

Implements the RetroAsset M0 foundation as a deterministic, hardware-authentic native retro-asset toolchain.

Core

• installable retroasset CLI and target/profile registry
• deterministic IR/manifest architecture; AI providers remain optional source-stage adapters
• target-family separation for raster and native character art
• machine-readable conversion reports with explicit lossiness

Amiga

• OCS/ECS/AGA profiles and validation
• native planar/raw, C and ASM exports
• IFF/ILBM encode/decode with ByteRun1
• independent ILBM consumer qualification
• m68k/AROS runtime qualification under FS-UAE

Character art / C64

• native ANSI/CP437 model, SGR parser/writer and SAUCE preservation
• native C64 PETSCII/screen-code model with color and reverse-video semantics
• screen RAM, color RAM and deterministic PRG viewer exports
• VICE headless runtime qualification using redistributable Open ROMs
• ATASCII reserved as a character-family extension point

OCI / CI

• Alpine-based non-root OCI image
• amd64 + arm64 multiarch publishing workflow for GHCR
• documented /work/input read-only and /work/output writable contract
• immutable sha-* tags intended for qualification
• unit, CLI, structural, independent-consumer and emulator qualification coverage

All M0 issues are completed and the current branch CI is green. No proprietary ROMs, AmigaOS files, malware samples or AI-provider credentials are included.

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