[Nyvo-io]

Summary

• move the renderer-visible window.maka shape into a preload-owned MakaBridge contract
• make the exposed preload object satisfy the shared contract and keep global.d.ts as a small global augmentation
• move attachment blob encoding out of src/main and preserve the existing byte wire format and IPC channels
• add dedicated preload typechecking and bridge contract coverage
• preserve the closed PermissionActionResult failure union across the preload contract and runtime bridge

Scope

This is behavior- and visually-neutral. It does not rename IPC channels, expand renderer capabilities, or change the exposed bridge surface. The contract is aligned with the existing runtime, including memory proposal methods and permission result shapes.

Part of #1084

Verification

• npx tsc -p apps/desktop/tsconfig.preload.json --noEmit
• npm --workspace @maka/desktop run build:preload
• focused bridge and attachment tests: 6 passed
• focused Desktop contract tests: 111 passed, with one pre-existing attachment rendering failure caused by the current LocaleProvider API mismatch
• npx biome lint on all changed source/test files
• git diff --check

The full Desktop typecheck remains blocked by pre-existing mainline issues: the current LocaleProvider prop migration, stale mcp navigation union values, and unavailable local @maka/mcp build declarations.

[Astro-Han]

Superseded by the approved review below.

[Astro-Han]

Closes #1084 will close the whole tracking issue when this PR merges, but #1084 still has many unchecked slices. Please change it to Part of #1084 or name the preload slice so the umbrella stays open.

[Astro-Han]

LGTM now. Merging!