fix(desktop): restore retained shared sessions

[M4n5ter]

Summary

English

• Persist the last authenticated shared-Session catalog projection with each retained Guest mount, so joined tasks are visible immediately after a cold Desktop restart while the Host reconnects.
• Reconcile retained mounts from the authoritative Host catalog after authentication, and collapse duplicates only after the Host proves they refer to the same State Root and Session.
• Keep retained-task status live and expose the actual selected Runtime Host stream path as WebRTC, QUIC, TCP, or member transit in both joined tasks and the Host list.
• Preserve the normal scoped sessions:changed contract for Session-semantic updates while using mount invalidation only to trigger inventory refreshes.
• Normalize Astryx's package-manager-specific generated header so the checked-in theme artifact is deterministic across local and CI installs.

中文

• 在访客挂载中保存最近一次由 Host 认证过的共享会话信息。Desktop 冷启动后，即使 Host 仍在重连，已经加入的任务也会立即回到会话列表。
• 连接恢复后，以 Host 返回的权威会话目录校准本地记录；只有 Host 已确认两个挂载属于同一个 State Root 和同一个 Session 时，才自动合并重复条目。
• 让“已加入的共享任务”实时更新连接状态，并在这里和 Host 列表中直接显示当前业务连接实际选中的 WebRTC、QUIC、TCP 或成员转发路径。
• 会话变化继续走原有的、按作用域隔离的 sessions:changed 语义；挂载变化只负责通知界面重新读取目录，避免出现第二套会话事件协议。
• 统一 Astryx 生成文件里随包管理器变化的说明注释，避免本机和 CI 对同一份主题源码生成不同结果。

Verification

• npm run check:tui-copy
• node --test scripts/check-tui-copy.test.mjs
• node --test scripts/biome-staged-check.test.mjs
• npm run lint
• npm run format:check
• npm run astryx:surface-inventory
• npm run astryx:surface-inventory:test
• npm run build
• npm run typecheck
• npm run astryx:theme -- --check
• Simulated npm, pnpm, Yarn, and Bun Astryx builder headers normalize to the same artifact
• npx knip --workspace apps/desktop
• npx knip --workspace packages/ui
• npm run check:renderer-architecture -- --base origin/main
• git diff --check origin/main...HEAD
• npm test — all workspace tests passed
• Focused shared-session, mount-projection, candidate, and shutdown coverage: 136 tests passed
• Parallel correctness and simplification reviews converged with no confirmed findings on the substantive source snapshot.

AI use

Select exactly one:

• No generative tool made a substantive contribution
• Generative tooling made a substantive contribution

Tool(s) and scope: Codex implemented the persistence, reconciliation, connection-path UI, and focused tests, then performed parallel correctness and simplification review cycles.

Checklist

• Tests cover the change and fail without it
• Lint, format, typecheck and the affected suites pass locally

Does this PR entail a change in behavior?

• Yes — described under Summary above
• No