feat: prepare Cedric workspace release

[almual1m]

Summary

• add the Cedric multi-tab workspace surface with Browser, file, code, markdown, Terminal, Side Chat, context handoffs, persisted tabs, and tab ergonomics
• add Background Tasks lifecycle visibility, persisted task snapshots, restart-orphan retry/recovery, live running detail, and workspace action requests
• wire the local Kimi bridge path and complete the internal scoped package rename to @cedric/*
• refresh docs, setup handoffs, SDK/OpenAPI output, and package hygiene needed for package-level validation

Validation

• bun install
• ./packages/sdk/js/script/build.ts
• cd packages/core && bun test test/background-job.test.ts
• cd packages/opencode && bun test test/background/job.test.ts test/server/httpapi-experimental.test.ts test/tool/workspace.test.ts test/tool/registry.test.ts
• cd packages/app && bun test --preload ./happydom.ts ./src/components/background-tasks.test.ts ./src/context/global-sync/bootstrap.test.ts ./src/pages/session/workspace-actions.test.ts ./src/context/workspace-tabs.test.ts
• cd packages/app && bun run build
• cd packages/desktop && bun run build
• declared package typecheck sweep from package directories
• no old scoped package matches in source/docs under the ignored-artifact filter
• git diff --check

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