sync: enforce connector execution and refresh workflow UX

[Luhaozhu]

Summary

• Enforce connector execution end to end: validate connector selections at the API boundary, carry the selected connector through orchestration, and require the matching connector tool call.
• Add direct automation-to-chat flows and preserve task context, plan history, queued-message behavior, and streaming status across refreshes.
• Replace the legacy homepage shortcut flow with configurable suggested questions and refine sidebar, chat, scrolling, mobile, and first-run interactions.
• Refresh the main Tauri desktop source to version 0.5.24 with first-launch provisioning and shell UX improvements.
• Remove the dedicated desktop-uos/ delivery client from the public CE tree, while retaining the main desktop/ client.

Complete comparison against public main

• Base: 704f8a37a7bf3f67166c67eb383da7cf83d377fb
• Head: 7aef9ee1dd415ca1b565632b95210c59d2d11676
• 94 files changed: 7 added, 57 modified, 30 deleted
• 2,017 insertions and 6,902 deletions
• Top-level distribution: src/ 50 files, desktop-uos/ 30 files (all removed), document/ 8 files, desktop/ 6 files

Verification

• Deterministic CE generation completed with required-runtime, forbidden-artifact, binary-asset, brand, path, and license gates passing.
• CE import, OpenAPI, ORM, and release regression checks passed.
• Final derived tree matches the generated dist/ce tree byte for byte, and git diff --check is clean.
• Node 22 CE frontend production build passed, including i18n checks, dark-mode checks, TypeScript compilation, Vite bundling, and precompression.
• Targeted shared-backend regression suite passed: 54 tests.
• Frontend UI regression and automation-conversation checks passed.

Desktop installer artifacts were intentionally not built or published as part of this sync; this PR contains source changes only for desktop targets.