Add MiniMax provider presets

[octo-patch]

Reason: Add built-in MiniMax presets with accurate regional endpoints and model capabilities.

This change:

• adds global and China presets for the chat and messages wire formats
• registers context, image/video input, and thinking metadata for MiniMax-M3 and MiniMax-M2.7
• preserves video attachments through selection, serialization, persistence, reload, rendering, and rewind

Checks:

• npm run build from apps/desktop
• npm test -- src/utils/__tests__/agentMessageAdapter.test.ts -t "preserves image and video attachments" from apps/desktop
• cargo test -p godcoder-agent-desktop provider_preset_tests --locked
• cargo check --workspace --all-targets
• cargo test --workspace --locked
• git diff --check