[JustSusie]

Assets can be decoded and encoded, but editing them and writing their containing files requires coordinated cloning, identity validation, offset updates, and bundle compression/encryption. This change adds clone-based editing and immutable editor branches for SerializedFile and UnityFS bundles.

Changes

• Emit typed Clone methods and guarded property setters; regenerate interfaces to support nested assignments while rejecting unavailable members.
• Add SerializedFileEditor with ordered edits, explicit type identity for additions, PathID allocation, reference validation, and cached materialization.
• Preserve original bytes for unchanged files and bundles; patch equal-length payloads and update object offsets/sizes for length changes.
• Add BundleEditor and connect UnityCN encryption to compressed-block output, preserving uncompressed blocks. Correct trailing block-info placement and partial incompressible-block sizes.
• Add temporary-file replacement and rollback-capable stream output. AssetWriter defaults to the source file's endianness.

Validation

• dotnet build UnityAsset.NET.sln -v:m --no-incremental: 0 warnings, 0 errors.
• dotnet test tests/UnityAsset.NET.Tests/UnityAsset.NET.Tests.csproj -f net10.0 --no-restore -v:q: 577 passed locally (565 existing tests plus 12 new local acceptance cases).
• Local acceptance coverage includes full-catalogue compilation, real MonoBehaviour byte round trips, nested edits, unchanged bytes, equal-length diff boundaries, length-changing readback, independent branches, added identities, reference rejection, partial-write rollback, and encrypted/unencrypted bundle layouts.

Review notes

400 of the 418 changed files are generated interface artifacts; the generator was first run into a temporary directory. The additional acceptance tests, documentation, and external fixtures are intentionally not included in this PR, pending separate review, so the 577-test count describes the local verification workspace rather than this branch alone.

Materialization currently buffers results in memory. Existing unsupported encoders remain unsupported. Stream rollback requires a seekable destination (and read access when overwriting); use the path overload for atomic file replacement.