refactor(dispatch): deliver tasks through Git worktrees

[bobleer]

Summary

• Show Dispatch only for Git workspaces, matching the worktree control visibility.
• Replace snapshot delivery with claimed controller baseline worktrees and isolated target-side Git worktrees.
• Provision missing Git objects through verified bundles and sync target commits back into the managed baseline with one action.
• Add protocol v3 workspace operations for SSH and account-device relay targets, including automatic verified SSH CLI setup and audit events.
• Make Dispatch sync retryable and idempotent, and restore observer transcripts, terminal timing, and cursor state correctly after controller restarts.
• Improve target loading, setup and sync messaging, and SSH connection-dialog behavior found during end-to-end testing.

Fixes: N/A

Type and Areas

Type: Refactor, feature, bug fix, UI/UX, documentation, tests

Areas: Rust core and services, CLI, desktop/Tauri, server/relay, Web UI, i18n, architecture docs

Motivation / Impact

Dispatch jobs now execute in isolated Git worktrees instead of copied snapshots. The controller keeps a claimed baseline worktree, target changes return as a verified Git bundle, and the user can synchronize them without mutating the original source checkout. The same contract is shared by SSH and account-device targets.

Compatibility

• Dispatch protocol v3 is intentionally incompatible with older target CLIs.
• SSH targets self-heal through verified CLI installation; account devices must run a compatible BitFun version.
• The first compatible signed stable CLI is pinned to 0.2.16. The real E2E run used a current-source Linux CLI because published 0.2.15 still implements protocol v2.
• Ignored files are not transferred; delivery is based on Git-visible workspace state.

Verification

• pnpm run type-check:web
• Focused Web UI suite: 16 files, 212 tests passed
• cargo check --workspace
• cargo test -p bitfun-cli workspace: 25 passed
• pnpm run i18n:audit: 0 warnings
• pnpm run fmt:rs
• git diff --check
• Real dev-desktop to SSH flow using pnpm run desktop:dev: target setup, dispatch execution, exact output, and initial bundle sync
• Repeated no-op sync, failed-operation retry, and three cold-start transcript recovery checks
• Confirmed controller baseline and remote worktree stayed clean at the same branch/head, and the user source checkout remained untouched

Reviewer Notes

• AI-assisted implementation; automated checks and the real cross-machine workflow were both completed.
• Manual UX verification used only the development desktop process, not the installed release application.
• The legacy snapshot result-apply path and its tar/flate dependencies are intentionally removed.

Checklist

• The change is focused and contains no secrets or local test artifacts.
• Focused frontend, Rust, i18n, formatting, and end-to-end verification are recorded above.
• New user-visible strings are localized in en-US, zh-CN, and zh-TW.
• Architecture and feature documentation are updated for the protocol and delivery-model change.