feat(dispatch): add detached SSH task execution

[bobleer]

Summary

• add the versioned bitfun dispatch protocol, crash-safe persistent job store, detached worker, explicit unattended approval policies, cursor events, and fail-safe PID/process-group cancellation
• add platform-neutral dispatch orchestration plus Desktop Tauri and Server Host adapters for SSH probe/install/submit/status/cancel/list flows
• add signed Linux/macOS CLI release assets and an owner-only, no-sudo SSH installer that verifies the checksum sidecar and archive with the shared minisign trust root
• add the Web target picker, install flow, observer-only session projection, reconnect/cursor replay, and fully drained terminal-state reconciliation

No linked issue.

Type and Areas

Type: Feature / UI/UX / CI / test

Areas: CLI, Rust core, SSH services, desktop/Tauri, Server Host, Web UI, release workflows, i18n

Motivation / Impact

This implements Dispatch Phase 1: a user can select an SSH execution target when creating a task, explicitly choose Auto or Reject-and-report approval behavior, and let the target-owned agent job continue after the dispatching Desktop process disconnects or exits. The dispatching client remains a submitter and read-only observer; it never acquires local workspace/runtime ownership or writes the remote session into its local session store.

Targets are intentionally limited to Linux and macOS over SSH in this phase. Account/relay device dispatch remains a later phase.

Verification

Passed after rebasing onto the latest upstream main:

• cargo check --workspace
• cargo test -p bitfun-cli dispatch --no-fail-fast — 43 passed
• cargo test -p bitfun-services-integrations --features remote-ssh-concrete remote_ssh::dispatch_ssh --lib — 13 passed
• cargo test -p bitfun-services-integrations --features remote-ssh-concrete remote_ssh::release_verify --lib — 3 passed
• pnpm run type-check:web
• pnpm --dir src/web-ui run test:run src/features/dispatch src/flow_chat/components/ChatInputWorkspaceStripLayout.test.ts src/flow_chat/services/FlowChatManager.test.ts src/flow_chat/services/flow-chat-manager/MessageModule.test.ts src/flow_chat/services/flow-chat-manager/SessionModule.test.ts src/flow_chat/store/FlowChatStore.test.ts — 11 files / 145 passed
• node --test scripts/relay/package-contract.test.mjs — 5 passed
• pnpm run check:github-config
• git diff --check upstream/main...HEAD

Additional completed checks:

• pnpm run i18n:generate && pnpm run i18n:contract:test && pnpm run i18n:audit
• pnpm run theme:color-audit:all
• pnpm run lint:web
• pnpm run check:repo-hygiene

Not yet performed: the clean Linux/macOS VM acceptance matrix covering first-time install, pkill -9 BitFun, Desktop restart/cursor replay, remote-only filesystem effects, and tampered-archive rejection.

Reviewer Notes

Architecture and safety invariants:

• target-side jobs and sessions are authoritative; outbound records are a separate observer index
• exact submit intent is idempotent, job.json is the final commit marker, and pre-worker controller crashes recover without replaying an ambiguous turn
• prompt JSON is staged through owner-only files/stdin, never shell argv
• installer and worker cancellation authenticate live process identity; an absent leader or unverified/reused PID/PGID is never signalled
• terminal UI fallback runs only after an empty same-cursor terminal page, clears late timers/runtime placeholders, and is idempotent with native terminal agent events

Known non-blocking follow-ups include Server Host message-size alignment, visible transcript-gap handling for log rotation/omitted events, canonical path alias handling, an in-progress install cancel affordance, unread-completion parity, and job/outbound retention/GC.

Checklist

• This PR is focused and does not include secrets, temporary prompts, generated scratch files, or unrelated artifacts.
• Relevant verification is recorded above, or skipped checks are explained.
• User-facing strings, docs, and locales are updated where applicable.